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UNIVERSnYgfCALIFORNIA 
COLLEGE  of  MINING 

DEPARTMENTAL 
LIBRARY 


BEQUEST  OF 


SAMUELBENEDICTCHRISTY 

PROFESSOR  OF 

MINING  AND   METALLURGY 
1885-1914 


''tt^~  *>  •  / 
of  %  |ftustum  of  Comparattbe 

AT    HARVAKD    COLLEGE. 

VOL.  XI.    PART  I. 


LITHOLOGICAL     STUDIES. 


A  DESCRIPTION  AND   CLASSIFICATION  OF  THE 
ROCKS  OF  THE   CORDILLERAS. 


BY  M.  E.  WADSWORTH. 

ii 


WITH    EIGHT    PLATES. 


CAMBRIDGE: 

far   tlje   ffluscum. 
OCTOBER,  1884. 


INTRODUCTORY    NOTE. 


I'MIKK  the  title  of  "  Litliological  Studies,"  ^a  work  is  here  presented  to  the  public 
which  is,  in  point  of  fact,  a  continuation  of  the  publications  of  the  Geological  Survey  of 
California,  begun  under  my  direction,  in  I860.  Had  that  Survey  been  completed,  the 
investigation  of  the  rocks  of  the  State  would  naturally  have  been  one  of  the  matters  to 
which  our  attention  would,  at  the  proper  time,  have  been  turned;  and,  after  the  stoppage 
of  the  Survey,  in  planning  for  the  elaboration  of  tin-  materials  in  my  hands,  I,  in  1877, 
determined  that  the  lithological  collections  which  I  had  accumulated,  and  which  repre- 
sented a  wide  area,  should  be  described  and  classified.  For  this  purpose  Dr.  Wadsworth 
was  selected  ;  and,  a  portion  of  his  results  being  now  ready,  it  is  thought  best  that  it  should 
be  published,  without  waiting  for  the  completion  of  the  entire  work.  It  will  undoubt- 
edly seem  to  the  reader  that  what  is  here  furnished  does  not  exactly  correspond  with 
or  carry  out  the  idea  suggested  on  the  title-page,  namely,  that  this  is  a  description  and 
classification  of  the  rocks  of  the  Cordilleras.  The  reason  is  this  :  Dr.  Wadsworth  having 
been  led  by  his  investigations  to  place  his  work  on  a  considerably  different  basis  from 
that  built  upon  by  other  lithologists,  has  found  it  desirable,  and  indeed  necessary,  to 
incorporate  in  it  results  obtained  from  the  study  of  material  not  furnished  by  the  Cor- 
dilleran  collect  ions.  In  the  portion  of  the  work  herewith  offered  to  the  public,  rocks  more 
basic  than  the  basalts  are  brought  under  consideration  ;  and  in  doing  this,  it  has  been 
found  that  it  was  not  possible  to  arrive  at  the  end  sought  to  be  gained  without  using  the 
materials  furnished  by  other  regions  and  by  other  lithologists.  Should  this  investigation 
be  continued  and  completed  —  as  it  is  hoped  will  be  the  case,  a  large  amount  of  work 
having  been  already  done  with  that  end  in  view  —  the  Cordilleran  collections  will  yield 
the  chief  portion  of  the  material  drawn  upon  for  the  remaining  portion  of  the  volume,  so 
that  it  will  be  found  that  the  work  is  essentially  based  on  the  collections  made  on  tin- 
western  side  of  the  North  American  continent,  the  study  of  which  gave  rise  to  the  ideas 

presented  in  this  first  part. 

J.   D.   \VH1TM.V 


(  '.\Mimii><,i:.    MASS..   (  Muln-r   1*.    1884. 


vi  CONTEXTS. 

origin  of  rocks  demanded  by  the  results  of  petrographical  study,  10.  The  asso- 
ciations of  different  rocks,  and  the  difficulties  in  their  separation,  10,  11.  'Iho 
microscopic  and  field  evidence  the  only  means  of  distinction,  10,  11.  Eruptive  and 
Sedimentary  Rocks  resemble  each  other  through  the  alteration  of  both,  11.  Sedi- 
mentary Eocks  presenting  peculiar  and  abnormal  conditions  not  proper  guides,  11, 

12.  Sedimentary  Rocks  found  not  to  present  the  microscopic  characters  of  Erup- 
tive ones,  12.      Requirements  necessary  to  prove  the  passage  of  a  Sedimentary 
into  an  Eruptive  Hock,  12.     Generally  positive  evidence  that  such  passage  does 
not  exist  can  be  obtained,  12,  13.     The  chemical  resemblance  of  Sedimentary 
and  Eruptive  Rocks  owing  to  the  derivation  of  the  former  from  the  latter,  13. 
Minerals  in  Lavas  of  prior  origin  to  the  consolidation  of  the  magma,  13  ;  not  de- 
rived from  Sedimentary  Rocks  and  characteristic  of  ancient  and  modern  Eruptives, 

13,  14.     Field  and  microscopic  evidence  opposed  to  the  theory  of  the  derivation 
of  Eruptive  from  Sedimentary  Rocks,  14;  the  demands  of  that  theory,  14.     Vol- 
canic or  eruptive  action  began  in  the  earliest  ages  of  the  Earth,  14  ;  this  action, 
although  intermittent,  is  a  dying  one,  14,  15.    The  older  Eruptives  the  same,  origi- 
nally, as  the  modern  ones,  15  ;  their  present  differences  due  to  alteration,  etc.,  15. 
Under  like  conditions  alteration  is  proportional  to  the  age,  15.     The  presence  of 
fragments  of  one  rock  in  another  is  alone  no  proof  of  difference  in  geological  age, 
15.     The  alteration  produced  by  internal  molecular  or  chemical  changes  in  the 
rock  mass  not  to  be  confounded  with  superficial  weathering,  15.     Metamorpliism 
not  extended  Pseudomorphism,  15.     Pseudomorphism  but  an  incidental  phase  in 
alteration,   15.     The  explanation  of  changes  in  rocks,  15,    16.     Metamorphisrn 
inversely  proportional  to  the  contained  silica  in  the  original  rock,  when  time 
and  other  conditions  are   the  same,    16.     Eruptive  Action,   including  Thermal 
Waters,  an  efficient  agent  in  Metamorphism,  16.     Metamorphism  dependent  on 
the  chemical  composition  of  the  rock  and  the  metamorphic  agents,  hence  lithe- 
logical  characters  no  criterion  for  determining  geological  age,  16.     The  constitu- 
ents of  rocks  pass  from  an  unstable  towards  a  more  stable  condition,  16;  this 
passage  a  factor  in  the  dissipation  of  energy,  16.     Rocks  are  produced,  grow  old, 
and  decay,  but  are  not  raised  again,  17.     Crystalline  Structure  no  proof  of  great 
age  or  of  great  depth,  1 7.     Long  time  not  always  allowed  for  the  formation  of 
fine-grained  and  fossiliferous  rocks,  17.     Contraction  tends  to  maintain  a  uniform 
temperature  in  the  Earth's  interior,  17,  18.     Relative  Progression  in  geological 
time  from  abundant  Acidic  to  abundant  Basic  Eruptives,  18.     All  Eruptives  de- 
rived from  the  Earth's  interior  material  which  had  never  solidified,  or  which  has 
since  been  reliquefied,  18.     SORBY'S  method  of  determining  the  origin  of  a  rock 
misleading,  18.     Association  of  Rocks  is  alone  no  proof  of  community  of  origin, 

18,  19.     Crystalline  Schists  naturally  occur  in  a  region  of  eruptive  rocks,  19. 
Definition  of  Lamination,  19  ;  this  structure  common  in  many  eruptive  rocks,  19. 
Joint  Planes  defined,  19;  often  mistaken  in  eruptive  rocks  for  Bedding  Planes, 

19,  20.     Cleavage  defined,  20.     Cleavage  common  both  in  Eruptive  and  Sedi- 
mentary Rocks,  20.     Foliation  defined,  20.     Foliated  Limestone  mistaken  for 
Mica  Schist,  20.    Foliation  and  Cleavage  produced  by  the  same  cause  at  Squantum, 
Mass.,  20,  21.     Foliation  common  in  altered  eruptive  rocks,  21  ;  the  planes  being 
at  right  angles  to  the  direction  of  pressure,  21.    Schistose  or  Fissile  Structure,  21. 
Fluidal  Structure  defined,  21.     Schistose  Structure  often  mistaken  for  Fluidal 
Structure,  21  ;  the  latter  mistaken  for  Planes  of  Sedimentation,  21.     Lines  of 
chemical  deposition  taken  for  fluidal  structure,  21.     Arguments  from  analogy  of 
doubtful  value,  22  ;  also  from  one  region  to  another,  22.     Evidence  not  sustain- 
ing the  divisions  of  the  Azoic  System,  22,  23.     Explanation  of  the  structure  of 


CONTENTS.  vii 

districts  of  Crystalline  Rocks,  22.  Application  of  current  views  in  American 
ecological  Literature,  23.  Association  of  Eruptive  and  Volcanic  Rocks,  23. 
Origin  of  Crystalline  Rocks,  23.  Application  of  current  views  to  Vesuvius  in 
the  time  of  STHABO,  24.  Principles  to  bo  employed  in  studying  regions  of 
Crystalline  Rocks,  24.  Materials  of  the  earliest  formed  Lauds  of  eruptive  origin, 
24.  Application  of  the  term  Eruptive  or  Volcanic  in  this  work,  24.  The  younger 
Volcanic  and  the  older  Plutonic  Rocks  form  a  continuous  series,  24. 

SECTION    III. 

Tin:  ORIGIN  AND  RELATIONS  OF  THE  MINERAL  CONSTITUENTS  OF  ROCKS  .    .     .    25-30 

The  constituents  of  rocks  fall  into  three  classes,  25.  Two  divisions  of  the  first 
rla-s,  -~) ;  action  of  the  Magma  on  Minerals  of  the  first  division,  25.  Inclusions 
in  eruptive  rocks,  25,  26.  Action  of  Lava  on  Inclusions,  26.  Microscopic  charac- 
ters of  Eruptive  Rocks  opposed  to  the  theory  of  their  derivation  from  Sediments, 
20.  Mineral  products  of  the  crystallization  of  a  magma,  26.  Mineral  products 
of  rock  alteration,  2C.  The  chemical  constitution  of  altered  rocks  not  essentially 
changed,  26.  Cause  of  rock  alteration,  27.  Alteration  a  character  of  the  rock 
mass  as  a  whole,  27.  Altered  eruptive  rocks  tend  to  simulate  the  features  of 
sedimentary  forms,  27.  The  general  tendency  of  rock  alteration,  27,  28.  The 
concentration  of  ores  in  rocks, and  veins  attendant  upon  rock  alteration,  28.  Ores 
of  mechanical  and  eruptive  origin  excepted,  28.  Theory  of  ore  deposits,  28. 
Mineralogy  and  Economic  Geology  chiefly  sciences  of  abnormal  minerals,  28. 
Unstable  character  of  eruptive  rocks,  28  ;  their  resemblance  to  chemical  labora- 
tories, 29  ;  passage  from  unstable  towards  more  stable  chemical  combinations,  29. 
Induration  not  always  an  indication  of  exposure  to  heat,  29.  The  glassy  state  of 
rocks  is  nearest  their  primitive  condition,  29.  Designations  employed  for  the 
three  classes  of  rock-forming  minerals,  29.  Distinction  of  cases  of  envelopment 
from  alteration  products,  29,  30.  Application  of  the  principles  of  Thcrmo-optics, 
30.  The  pyroguostic  characters  of  a  mineral  have  little  or  nothing  to  do  with  its 
condition  before  its  formation,  30.  The  conditions  under  which  minerals  crystal- 
lize from  a  cooling  magma  are  different  from  those  under  which  vein  and  altera- 
tion minerals  are  formed,  30. 

SECTION    IV. 

CHEMICAL  ANALYSIS  OF  ROCKS 31,32 

Chemical  Analysis  unable  to  determine  the  mineral  constituents  of  rocks,  31, 
32.  While  Chemical  Composition  remains  nearly  constant,  great  variation  exists 
in  the  structure  and  mineral  constituents,  31.  What  Chemical  Analysis  can  do 
for  the  lithologist,  31.  Relation  of  Chemical  Analysis  of  normal  rocks  to  rock 
species,  32.  Analyses  should  be  written  in  terms  of  the  elements,  instead  of  their 
compounds,  32. 

SECTION    V. 

CLASSIFICATION  BASED  ON  MINERAL  COMPOSITION 33-45 

Basis  of  the  common  classifications  of  rocks,  33  ;  minerals  used,  and  data  re- 
quired, 33.  —  THE  FELDSPARS,    33-43.      Their  different   modes   of  origin,    33. 
feldspar  theory,  33,34;  DELESSE'S  views,  34 ;  HKUMANN'S  molecular 


viii  CONTENTS. 

theory,  34.  WALTERSHAUSEN'S  theory,  34.  Krablite  a  rock,  and  not  a  mineral,  34, 
35.  BUNSEN'S  view  of  Baulite,  35.  HUNT'S  theory  of  the  feldspars,  35.  TSCHER- 
MAK'S  theory,  35,  36  ;  STRENG'S  views,  36  ;  PETERSEN'S  objections  to  TSCHERMAK'S 
theory,  37.  DANA'S  method  of  accounting  for  variations  in  feldspars,  37. 
HUNT  claims  to  have  originated  TSCHERMAK'S  theory,  37.  HUNT'S  alteration  of 
his  direct  quotation,  37.  HUNT'S  theory  not  original  with  him,  and  not  the 
same  as  TSCHERMAK'S,  37.  Writers  who  through  misapprehension  have  acknowl- 
edged HUNT'S  claims,  37,  38 ;  SILLIMAN  charges  TSCIIERMAK  with  appropriation  of 
HUNT'S  views,  38  ;  LEEDS  recognizes  the  difference  between  the  views  of  HUNT  and 
TSCHERMAK,  38.  The  charges  of  appropriation  made  against  TSCHERMAK  false,  38. 
DESCLOIZEAUX  on  the  optical  properties  of  the  feldspars,  38 ;  FRIEDEL'S  theory 
of  their  chemical  constitution,  38 ;  VOM  RATU'S  views,  38,  39.  DESCLOIZEAUX'S 
discovery  of  microcline,  39.  MALLARD  and  LEVY  teach  that  it  is  the  same  as  or- 
thoclase,  39.  SCHUSTER'S  observations  on  the  optical  properties  of  the  feldspars, 
39.  Feldspars  not  suitable  to  found  specific  distinctions  upon,  39.  No  means 
of  positively  determining  the  feldspar  species  in  rocks,  40.  DESCLOIZEAUX'S 
method  of  determining  feldspars,  40;  PUMPELLY'S  modification  of,  40,  41  ;  PUJI- 
PELLY  anticipated  by  LEVY,  41.  The  work  of  both  independent,  41.  HAWES  on 
the  distinction  of  feldspars,  41.  BURICKY'S  micro-chemical  method,  41,  42. 
SZABO'S  method,  42.  GEO.  H.  EMERSON'S  invention  of  a  method  of  distinguishing 
minerals  by  means  of  crystals  formed  in  blowpipe  beads,  42 ;  "amplified  later  by 
GUSTAV  ROSE,  \V.  A.  Ross,  and  H.  C.  SOKBY,  42.  The  specific  gravity  method  for 
determination  of  the  feldspar  species,  42.  Objections  to  the  above  methods,  42, 
43.  The  twinning  not  constant  in  feldspars,  43.  The  chief  value  in  lithology  of 
the  determination  of  the  feldspars,  43.  —  THE  PYROXENE-AMPHIBOLE  GROUPS,  44, 
4:5.  A  variable  series  in  them  as  in  the  feldspars,  44.  Cleavage  not  a  satisfac- 
tory basis  for  separating  Diallage  from  Augite,  44.  Augite  found  in  Basic  and 
Acid  Rocks,  and  in  the  older  and  younger,  44.  Alteration  of  Angite,  44.  Sec- 
ondary origin  of  some  Pyroxenes,  44.  Relation  of  Hornblende  and  Augite,  44. 
The  same  hand  specimen  both  a  Diorite  and  Diabase,  44.  The  Mica  Series,  45. 
Secondary  origin  of  Chlorite  and  Epidote,  45.  —  MINERALOGICAL  NOMENCLATURE 
OF  ROCKS.  Rock  Classification  based  on  mineralogy  alone,  impracticable,  45. 
Rock  Structure  valueless  for  specific  distinctions,  45. 

SECTION   VI. 

NAMING  ROCKS  ACCORDING  TO  THE  GEOLOGICAL  AGE 45-47 

Such  nomenclature  not  natural,  45.  No  line  can  be  drawn  at  the  Tertiary  Age, 
46.  Alteration  under  like  conditions  proportionate  to  age,  46.  The  petrogra- 
pher's  duty,  46.  The  presence  of  Fluid  Cavities  in  rocks,  46.  VOGELSANG  and 
JULIEN  on  Fluid  Cavities,  46.  Fluid  Cavities  sometimes  original  and  sometimes 
secondary  in  rocks,  46.  Occurrence  in  Tertiary  Rocks,  46.  The  cause  of  the 
Crystalline  Structure  in  the  older  rocks,  46,  47.  The  Granitic  Structure,  47. 

SECTION  VII. 

METHODS  OF  CLASSIFICATION 47-51 

Classification  the  framework  of  any  descriptive  science,  47.  The  mineralogical 
method  of  studying  rocks,  47.  The  natural  method,  47.  The  relation  of  miner- 
als to  rocks,  47,  48.  Meaning  of  the  Natural  Classification,  48.  Characterization 


CONTENTS.  ix 

of  the  Mincnilogical  Classifications  of  rocks,  48,  49.  Compared  with  zoological 
methods,  49.  Question  of  methods,  50.  Earlier  publication  of  these  principles, 
50.  European  classifications  based  largely  ou  altered  rocks,  50.  To  express 
perfectly  the  Natural  Classification  of  rocks  requires  perfect  knowledge  of  them, 
50.  The  classification  here  introduced  empirical,  50,  51.  Elasticity  of  the  classi- 
fication, 51 ;  its  fundamental  principles,  51. 

SECTION  VIII. 

THE  PRINCIPLES  OF  CLASSIFICATION 51,  52 

SECTION  IX. 
GENERAL  CONCLUSIONS  IN  REGARD  TO  SYSTEMS  OF  LITHOLOGICAL  CLASSIFICATION  53-59 

Universal  law  of  degradation  of  energy,  53.  Natural  classification  conforms  to 
it,  53.  The  demands  of  Petrography,  53.  Expansion  of  materials  in  passing  from 
the  liquid  to  the  solid  state,  53.  Pressure  tends  to  render  the  Earth's  interior 
solid,  53.  Sinking  of  the  Earth's  crust,  53.  The  structure  of  the  Earth  indicated 
by  petrographical  and  geological  facts,  54.  Crystalline  rocks,  54.  Systems  of 
classification,  54,  55.  Chemical  analyses  of  rocks,  56.  Alteration  of  rocks,  56. 
Divisions  of  minerals  and  rock  fragments  in  rocks,  56.  The  order  of  arrange- 
ment of  rocks,  57.  Determination  of  a  rock  by  means  of  its  unaltered  ground- 
mass,  57.  Practical  application  of  the  principles  of  nomenclature  and  classifi- 
cation, 57.  Specific  and  varietal  names,  57.  The  use  of  the  terms  Melaphyr, 
Diabase,  and  Diorite,  57,  58.  Sub-varietal  names,  58.  Trivial  names,  58. 
Arrangement  of  the  fragmental  rocks,  58.  Arrangement  of  rock  names,  58,  59. 
Varietal  and  sub-varietal  names  not  essential,  59.  Use  of  a  binomial  and 
trinomial  nomenclature,  59. 


CHAPTER    II. 

THE  SIDEROLITES  AND  PALLASITES. 
SECTION  I. 

SlDEROLITE GO-G8 

Definition  of  SIDEROLITE,  60.  Shingle  Springs,  Eldorado  Co.,  California,  60. 
Stanton,  Virginia,  60,  61.  Coahuila,  Mexico,  61.  Gibbs  meteorite,  Texas,  61. 
Butler,  Missouri,  61.  Toluca,  Mexico,  61.  General  structure  of  meteoric  sidero- 
lites,  61;  constituents  of,  61.  Widmannstattian  figures  developed  in,  62;  also  in 
Greenland  iron,  62.  Eeferences  to  illustrations  of  Widmannstiittian  figures,  62. 
Further  divisions  of  the  Siderolites,  62  ;  chemical  analyses  of,  62,  63 ;  specific 
gravity  of,  63  ;  Iron  in,  63  ;  Nickel  and  Cobalt  in,  63,  64  ;  minor  elements  in,  64. 
Terrestrial  Siderolites,  64,  65.  Greenland  iron,  65  ;  its  origin,  65.  Doubtful  me- 
teoric origin  of  many  Siderolites,  65.  Chemical  analysis  made  sole  test  of  mete- 
oric origin,  65,  66.  Origin  of  masses  of  meteoric  iron,  66  ;  TSCIIERMAK'S  views,  66  ; 


X  CONTENTS. 

SORBY'S  conclusions,  GG,  07  ;  objections  to  their  theories,  07.  The  organic  origin 
of  meteoric  iron  and  graphite,  07.  MASKELYNE'S  use  of  the  term  Siden/lite,  G8. 
The  terms  Siderite  aud  Jlolosiderite,  08. 

SECTION   II. 

PALLASITE 68-83 

GUSTAV  ROSE'S  use  of  the  term,  08.  Definition  of  Pallasite,  08  ;  arrangement  of, 
G8.  —  THE  METEORIC  PALLASITES,  69-75.  Tucson,  Arizona,  69.  Hemalga,  Peru, 
69.  Berdjansk,  Russia,  69.  Deesa,  Chili,  70.  Atacama,  Bolivia,  70.  Bitburg, 
Prussia,  70.  Hommoney  Creek,  North  Carolina,  71.  Singhur,  India,  71.  For- 
syth,  Missouri,  71.  Anderson,  Ohio,  71.  Krasnojarsk,  Siberia,  71,  72.  Potosi, 
Bolivia,  72.  Rittersgrun,  Saxony,  72.  Breitenbach,  Bohemia,  73.  Steinbach, 
Saxony,  73.  Atacama,  Chili,  73.  Sierra  de  Chaco,  Chili,  73.  Newton  Co.,  Arkan- 
sas, 74.  Meyelloues,  Bolivia,  74.  Hainholz,  Westphalia,  74.  Lodrau,  India, 
74,  75. 

VARIETY.  —  Cumberlandite,  75-83. 

Iron  Mine  Hill,  Rhode  Island,  75-79.  State  of  the  Iron  of  but  little  impor- 
tance lithologically,  76.  Microscopic  veins,  76.  Hercynite  (1),  77.  Tracing 
altered  conditions  of  Cumberlandite,  77-79  ;  specific  gravity  of,  79  ;  diminish- 
ing specific  gravity  with  alteration,  80.  First  published  description  of  Cumber- 
landite, 80.  Study  of  other  iron-bearing  rocks,  80,  81.  Tabcrg,  Sweden,  81. 
General  description  of  Pallasite,  81  ;  of  Cumberlandite,  81,  82.  Chemical 
analyses  of  Pallasite,  82,  83.  Chemical  analysis  alone  suggests,  but  does  not 
prove,  the  specific  relations,  83. 


CHAPTER    III. 

THE   PERIDOTITES. 

SECTION   I. 

INTRODUCTORY 84,  85 

ROSEXBUSCH'S  use  of  the  term  Peridotite,  84.  How  employed  in  this  work,  84. 
Order  of  arrangement  in  the  Peridotites,  84.  The  ueedlessness  of  subdivisions  of 
Peridotite,  84  ;  yet  subdivided  here  in  conformity  to  general  usage,  85.  Defini- 
tion of  Dunite,  85.  Proposal  of  the  name  Saxonite,  85.  Definition  of  Lherzolite, 
85.  Proposal  of  the  name  Buclmfrite,  85.  Definition  of  the  terms  Eulysite, 
Picrite,  Serpentine,  Porodite,  and  Tufa,  85. 

SECTION    II. 
THE  METEORIC  PERIDOTITES 86, 106 

VARIETY.  —  Dunite,  80. 
Chassigny,  France,  86;  glass  in,  86,  105. 


CONTENTS,  xi 

VARIETY.  —  Saxonite,  SG-94. 

Iowa  Co.,  Io\v;i,  Sii-SS.  Origin  of  the  chomlritiu  structure,  80,  87.  Occurrence 
of  a  base  in  meteorites,  87.  Dliurmsulii,  India,  88.  Kuyahinya,  Hungary,  88-91  ; 
nrgank'  remains  in,  s'.i.  The  constitution  of  meteorites  such  that  they  could  not 
have  existed  in  conditions  suitable  for  life,  91.  Choudritic  structure,  91. 
( Inadenfrei,  Silesia,  91,  92.  Gopalpar,  India,  92;  feldspar  in  it  doubtful,  92. 
Bntsnra,  India,  92,  93.  Lance,  France,  93.  Touriuues-la-Grosse,  Belgium,  93. 
Wacondo,  Kansas,  93,  94.  Goalpara,  India,  94. 

VARIETY.  —  Lherzolite,  94-101. 

Pultusk,  Poland,  94,  95.  New  Concord,  Ohio,  95,  96.  Mocs,  Transylvania, 
96.  Zsadany,  Banat,  96,  97.  Estherville,  Iowa,  97-101.  Iron  globules  in,  97, 
98.  1'eckhainitc,  99,  101.  MI:I;NII:K'S  theory  of  the  origin  of  the  Estherville 
meteorite,  99,  100;  objections  thereto,  100.  Variations  in  structure  of  this 
meteorite,  100,  101. 

VARIETY.  — Buchnerite,  101,  102. 

Tieschitz,  Moravia,  101,  102.  Peculiar  character  of  its  chondri,  101.  Hungen, 
(Jenuany,  102.  Grosuaja,  Caucasus,  102.  Alfianello,  Italy,  102. 

MISCELLANEOUS,   103-105. 

Bavarian  Meteorites  :  Mauerkirschen,  Eichstadt,  Schouenberg,  and  Krahcn- 
berg,  103.  Caharras  Co,  North  Carolina,  103,  104.  Mezo-Madaras,  Transyl- 
vania, 104-.  Alessandria,  Piedmont,  104.  llenazzo,  Italy,  104 ;  special  study 
should  be  made  of  this  form,  104.  Linn  Co.,  Iowa,  104.  Ausson,  France,  104. 
Nanjemoy,  Maryland,  104.  Drake  Creek,  Tennessee,  104.  L'Aigle,  France,  105. 
"SVeston,  Connecticut,  105.  Chateau  Henard,  France,  105.  Hessle,  Sweden,  105. 
Nobleboro',  Maine,  105. 

VARIETY.  —  Tufa,  105,  106. 
Orviuio,  Italy,  105,  106.     Chantonnay,  France,  106. 

SECTION    III. 

THE  METEORITES.  —  THEIR  ORIGIN  AND  CHARACTER 106-118 

MASKELY.VE'S  teachings,  106,  107.  SORBY'S  views,  107,  108.  FORBES'S  micro- 
scopic observations,  108.  MEUNIER'S  theory  and  FORBES"  s  criticism  of  it,  108,  109. 
'\'~-(  HKKMAiv's  idea  of  the  tufaceous  character  of  meteorites,  and  their  eruptive 
origin,  109,  110.  Objections  to  the  preceding  views,  110-112.  The  Chondritic 
Structure  limited  to  a  certain  chemical  and  mineralogical  type  of  meteorites,  110. 
Continuity  of  the  Chondri  and  Matrix,  110,  111.  Structure  of  meteorites  rarely 
fragmented,  111,  112.  Chondritic  Structure  produced  by  rapid  crystallization, 
111.  Enclosures  in  meteorites,  111,  112.  Meteorites  derived  from  liquid,  not 
solid  material,  112,  113.  The  Sun,  or  some  similar  body,  their  most  probable 
source,  112.  Community  of  elements  in  the  Sun  and  Meteorites,  112.  Possi- 
bilities of  Meteorites  being  thrown  from  the  Sun,  113.  Probable  liquid  condition 
of  the  Sun,  113.  Meteoric  constitution  of  some  astronomical  objects,  113.  The 
theory  that  Meteorites  are  thrown  from  the  Sun  is  old,  113,  114.  Abundance  of 
Metallic  Meteorites  in  past  times,  I  1  1.  Meteorites  not  thrown  from  the  Moon, 
111.  and  imt  from  the  Earth  in  past  times,  11  I.  Need  of  further  careful  study 


xii  CONTEXTS. 

of  meteorites,  114,  115.  Objections  to  SORBY'S  view  that  minerals  of  unlike  spe- 
cific gravity  can  intercrystallize,  115.  Objections  to  HELMHOLTZ'H  theory  that  the 
Earth  is  composed  of  meteoric  fragments,  115,  116.  Boulders  in  Northern  Drift, 
fallen  Meteorites,  110.  Unscientific  to  suppose  Meteorites  have  brought  germs 
of  life  to  the  Earth,  116.  Destruction  of  germs  by  the  cold  of  space,  116. 
Meteorites  not  exposed  to  action  of  water  and  air,  116.  Meteorites  not  vein  for- 
mations, 117.  Source  of  metals  in  veins,  117.  Copper  in  Meteoric  Rocks  and 
Terrestrial  Basic  ones,  117.  Metallic  Iron  in  Terrestrial  Basic  Rocks,  117. 
Nickel,  etc.  in  Meteoric  and  Terrestrial  Masses,  118. 

SECTION    IV. 
THE  TERRESTRIAL  PEUIDOTITES 118-162 

VARIETY.  —  Dunite,  118-125. 

Franklin,  North  Carolina,  118;  structure  indicates  eruptive  origin,  118. 
Webster,  North  Carolina,  and  alterations  in,  119,  120.  Tafjord,  Norway,  120. 
Dun  Mountain,  New  Zealand,  121.  Sondmiire,  Norway,  12L  Eobcrgvik,  Nor- 
way, 121.  Bonhomme,  France,  121,122.  Karlstiitten,  Austria,  122.  Tron,  Nor- 
way, 122.  Heiersdorf,  Saxony,  122.  Ronda  Mountains,  Spain,  122, 123.  Serrania 
de  Ronda,  Spain,  123.  St.  Paul's  Rocks,  their  origin  and  alterations,  123-125. 

VARIETY.  —  Saxonite,  125-128. 

Russdorf,  Saxony,  125.  Northern  Norway,  125,  126.  Thorsvig,  Norway,  126. 
Birkedal,  Norway,  126.  Hovenden,  Norway,  126.  Rodfjeld,  Norway,  126. 
Andestad  See,  Norway,  126,  127.  Langenberg,  Saxony,  127.  Callenberg, 
Saxony,  127.  The  Ziegelei,  Saxony,  127.  Fatu  Luka,  Timor,  127.  Eofna,  Alps, 
127,  128. 

VARIETY.  —  Lherzolite,  128-147. 

Lake  Lherz,  France,  128,  129.  Serram'a  de  Ronda,  Spain,  129.  Italy,  129. 
Ultenthal,  Tyrol,  129.  Colusa  Co.,  California,  129-132;  alteration  structure  in, 
taken  for  stratification,  130.  Inyo  Co.,  California,  132.  Production  of  Magnetite 
during  alteration,  132.  Mohsdorf,  Saxony,  132,  133.  Rodhaug,  Norway,  133. 
Baste,  Harz,  133,  134.  Christiania,  Norway,  134.  Gj0rud,  Norway,  135.  Presque 
Isle,  Michigan.  136-138.  Formation  of  dolomitic  rocks,  137,  138.  Eruptive 
origin  of  this  Peridotite,  138.  Ishpeming,  Michigan,  139.  Dolomitic  rocks,  139. 
Transylvania,  Austria,  139,  140.  Fichtelgebirge,  Bavaria,  140.  Jaina  River, 
San  Domingo,  140.  Starkenbach,  France,  140.  Todtmoos,  Baden,  141.  Plumas 
Co.,  California,  142.  Levauto,  Italy,  142.  Euboca,  142.  Philippine  Islands, 
143.  Lizard  District,  Cornwall,  143.  Troad,  Asia  Minor,  143-147.  Dikes  of 
Serpentine,  144.  Diallage  with  Cleavage  of  Augite,  145.  Schistose  Rocks  and 
their  origin,  146,  147. 

VARIETY.  —  Eulysite,  147-149. 

Tunaberg,  Norway,  147.  Kettilsfjall,  Sweden,  147, 148.  Varallo,  Sesia  Valley, 
148.  Lepce,  Austria,  148.  Fontanapass,  Greece,  148.  Mohsdorf,  Saxony,  148. 
Gillsberg,  Saxony,  148,  149. 

VARIETY.  —  Ficrite,  149-152. 

Austria,  149.  Steierdorf,  Banat,  149,  150.  Inchcolm  Island,  Scotland,  150. 
Herborn,  Nassau,  150.  Ellgoth,  Austria,  150,  151.  Anglesey,  151.  Dillgend, 
Nassau,  151,  152. 


CONTENTS.  xiii 

VARIETY,  —  Serpentine,  1">:>~161. 

Fitztowu,  Pennsylvania,  1">L'.  Frankenstein,  Sik-sia,  152.  Leko,  Norway,  152. 
\\ 'aldheim,  Saxony,  153.  Thessaly,  153.  Santiago,  San  Domingo,  153,  154. 
La  \Yga,  Sun  Domingo,  151.  I'.rixlegg,  Tyrol,  154.  II  Piano,  Elba,  154,  155. 
Tasmania,  15.").  Windisch-Matrey,  Tyrol,  155.  St.  Sabine,  France,  155,  156. 
River  ( (isuin,  Timor,  156.  Riviere  ties  Plantes,  Canada,  156.  Melbourne,  Canada, 
156.  Caliria.  Spain,  150.  High  Bridge,  New  Jersey,  156,  157.  Zoblitz,  Sax- 
ony, l-">7,  l.'is.  Chip  Flat,  California,  158.  Depot  Hill,  California,  158.  Plumas 
Co.,  California,  158.  Finland,  158.  Klopfberg,  Austria,  159.  Nezeros,  Thes- 
saly, 159.  Fatn  Temanu,  Timor,  159.  Westficld,  Massachusetts,  159,  100. 
Formation  of  Talc,  159.  Lynnfield,  Massachusetts,  160.  Hiver  Joa,  San 
Domingo,  160.  Newport,  Vermont,  161.  Celinac,  Austria,  161.  Texas,  Penn- 
sylvania, 161.  Chester,  Pennsylvania,  161. 

VARIETY.  —  Porodite,  161,  162. 
Fatu  Luka,  Timor,  161,  162.     Strand,  Timor,  162. 

SECTION   V. 
PERIDOTITE. — ITS  MACROSCOPIC  CHARACTERS 162-165 

Structure  of  the  Meteoric  Peridotites,  162.  Structure  of  the  Terrestrial 
Peridotites,  163-165;  least  altered  forms,  163;  alteration  characters,  163.  Ap- 
pearance of  the  Olivine  Groundmass,  163.  Alteration  of  the  Pyroxene  Minerals, 
163,  164.  Segregations  in  Serpentine,  164.  Translucency  of  Serpentine,  164. 
"  Slickensides "  in  Serpentine,  164.  Products  of  extended  alteration  in  Perido- 
tite,  164.  Term  Serpentine  in  Mineralogy,  164.  Variability  of  Serpentine,  164; 
Schistose  Structure  in,  164.  Production  of  Talc  and  Actinolite  Schists,  164,  165  ; 
of  Dolomitic  Limestones,  165.  Fragmentul  states  of  Peridotite,  165.  Origin  of 
Ophicalcites  and  hrecciated  Serpentines,  165.  Introduction  of  the  terms  Merolite 
and  Merolilic  for  pseudo-fragmental  rocks,  165. 

SECTION  VI. 
TERIDOTITK.  —  ITS  MICROSCOPIC  CHARACTERS 165-175 

General  Microscopic  Structure  of  the  Meteoric  Peridotites,  165-167.  The  Base 
of,  166.  The  Chondri  of,  166.  The  Olivine  of,  166.  The  Enstatite  of,  166. 
The  Iron  and  Pyrrhotite  of,  166,  167.  The  Chromite  and  Picotite  of,  166. 
The  Manbhoom  Saxonite,  167.  Union  of  Diallage  and  Augite  Cleavage  in  Dial- 
lage,  167.  Lherzolite,  167.  Minor  minerals  in  Meteoric  Peridotites,  107.  Frag- 
mental  Meteorites.  187.  Microscopic  characters  of  the  Terrestrial  Peridotites, 
168-175;  of  Dunite,  168;  alteration  to  Serpentine,  168.  Transition  in  the 
varieties  of  Peridotite,  168.  Characters  of  Enstatite,  168,  169  ;  of  Diallage,  169  ; 
of  Augite,  169.  Alteration  of  the  Pyroxene  Minerals,  109.  Description  of  the 
alterations  in  the  Peridotites  as  shown  in  the  plates,  109-172.  The  ffozoim  ques- 
tion, 172-174.  Organic  structure  simulated  in  Felsites,  173.  The  supposed 
•''in,  and  other  organisms,  the  more  perfect,  the  more  the  rock  is  altered,  173. 
The  inclination  to  unduly  extend  one's  line  of  study,  17li,  171.  Crucial  test  in 
disputed  problems,  174.  The  KO-MHI  in  segregated  or  veinstone  deposits,  there- 
fore not  of  organic  origin,  174.  Microscopic  charaet.-ra  of  Picrite,  174,  175. 


XIV  CONTENTS. 

Obliteration  of  original  characters  in  the  process  of  the  alteration  of  Peridotites, 

175.  Production  of  Schistose  Structure  in,  175.     The  supposed   conversions  of 
Schists  into  Serpentine,  175.     Absence  of  the  Mesh  Structure  and  Chromito  or 
Picotite  in  Serpentine  due  to  alteration,    175.     Formation  of  Serpentine  Vein- 
stones, 175.     Alteration  minerals  in  Peridotite,  175.     Ground  covered  by  the 
text,  175. 

SECTION    VII. 

ClIROMITE   AND   PlCOTITE. — THEIR   RELATIONS 170-186 

FISCHER'S  observations,  176.     DATHE'S  studies,  170.     THOULET'S  observations, 

176.  Translucency  of  Chromite  first  remarked  in  1825,  by  C.  H.  PFAFP,  176.    The 
writer's  observations  on  some  eighty  specimens  of  Chromite,  Picotite,  and  Ores  of 
Iron,  177-180.    Color  and  lustre  of  massive  Chromite,  180.    Hardness  and  streak 
of  Chromite  and  Picotite,  180.     Specific  gravity  of,  180.     Coffee-broim  color  of, 
180.     Variability   in   color   of,    180,    181.      Observation  of  translucency,   181. 
Preparation  of  specimens,   181.     Chemical  relations   of  Chromite  and  Picotite, 
181-183.     Views  of  GENTH  and  RAMMELSBERG  on,  183.     Microscopic  relations  of, 
183,  184.     Conclusions  regarding  mineral  species  and  their  variability,  184,  185. 
A  natural  system  in  mineralogy,  185.     Strange  history  of  a  Chromite  Analysis, 
185,  186.     Errors  in  published  lists  of  Analyses,  186. 

SECTION   VIII. 

PERIDOTITE. —  ITS  CHEMICAL  CHARACTERS 18G-189 

Designation  of  the  varieties  of  Peridotite,  186.  Specific  gravity  of,  186,  187. 
The  Carbonaceous  Meteorites,  186.  As  specific  gravity  decreases,  the  Iron  dimin- 
ishes and  Magnesia  increases,  187.  Microscopic  characters  of  the  Cold-Bokkeveld 
Meteorite,  186.  Percentage'  of  silica  in  Pallasite,  187 ;  of  silica  in  Peridotite, 
187,  188.  Special  case  of  the  Cabarras  Meteorite,  187.  Percentages  of  alnminia, 
iron,  lime,  and  magnesia  in  Peridotite,  188.  The  meteoric  forms  richest  in  Iron,  1 88. 
Alteration  leads  to  decrease  in  the  percentage  of  Iron,  188.  Relation  of  Picrite 
to  Basalt,  188.  Minor  elements  in  Peridotite,  188.  Water  proportioned  to  the 
amount  of  alteration,  188,  189.  General  chemical  characters  of  Peridotite,  189. 


SECTION   IX. 

PERIDOTITE.  —  ITS  ORIGIN 189-192 

Eruptive  occurrence  of  Peridotite  in  the  Cornwall,  Troad,  and  Lake  Superior 
districts,  189.  Relations  of  Schistose  Rocks  and  Peridotes,  189,  190.  Associa- 
tion of  Eruptive  and  Schistose  Rocks,  189.  The  Schists  produced  by  alteration 
of  Peridotite,  189,  190.  Detritus  of  Eruptive  Rocks,  190.  Pcridotic  Volcanoes, 
190.  Expected  occurrence  of  Peridotites,  190  ;  difficulty  of  the  study  of,  190. 
Production  of  Serpentine  by  alteration  of  Peridotite,  190.  Migration  of  mineral 
matter,  190.  Chemical  precipitation  of  Serpentine  from  ocean  waters,  190.  Con- 
fusion between  migrated  serpentine  material  and  that  produced  by  alteration 
in  situ,  190.  Serpentine  question  allied  to  the  phenomena  of  Eruptive  Rocks  and 
Veinstones,  190,  191.  No  proof  that  the  Canadian  Serpentines  are  stratified 
sedimentary  deposits,  191.  Believed  inaccuracy  of  DR.  HUNT'S  writings,  191. 


CONTENTS.  XV 

Production  of  Serpentine  through  alteration  of  other  rocks  than  Peridotitc,  191. 
Literature  of  the  Serpentine  question,  191.  Talcose  Rocks  derived  from 
IVridotites,  191,  192.  Steatite  Hocks  alteration  forms  of  Gabbro  and  Diabase 
(Diorite),  192.  Actinolite  and  other  schists  derived  from  Peridotite,  192.  Am- 
jihilm  h  •  Schists,  192.  Origin  of  Magnesian  Limestoues,  192.  Explanation  of  the 
alterations,  192. 

SECTION  X. 

PERIDOTITE. —  ITS  CLASSIFICATION 192-194 

The  use  of  Specific  and  Varietal  Names,  192.  Definition  of  Peridotite,  192. 
Basis  of  varietal  distinctions,  193.  Definition  of  the  varieties,  193.  Alteration 
varieties  subordinate  to  the  original  niineralogical  ones,  193.  Probable  varieties 
to  be  found  by  future  study,  193.  Most  variety  names  not  important,  193. 
Limburyite  of  ROSENBUSCH,  193.  Terms  applied  to  the  fragmental  forms  of 
IVridutitc,  193,  194.  Tabular  Classification  of  Siderolite,  Pullasito,  and  Perido- 
tite, 194.  Essential  terms  in  describing  Peridotites,  194. 


CHAPTER  IV. 

THE  BASALTS. 

SECTION   I. 
THE  METEORIC  BASALTS 195-200 

VARIETY.— Basalt,  195,  196. 

Stannern,  Moravia,  195.  Constantinople,  Turkey,  195.  Jonzac,  France,  196. 
Petersburg,  Tennessee,  19C.  Frankfort,  Alabama,  196. 

VARIETY.  —  Gabbro,  196-205. 

Luotolaks,  Finland,  196.  Massing,  Bavaria,  197.  Juvenas,  France,  197. 
Shcrgotty,  India,  197,  198.  Maskelynite,  198.  Piiwlowka,  Russia,  198.  Lo 
Teillcnl,  "France,  198.  Bishopville,  South  Carolina,  199-201..  Chladnite,  199. 
Aqueo-igncous  origin  of  Eruptives,  201.  Mancgaum,  India,  201,  202.  Busti, 
India,  202.  Shalka,  India,  202.  Ibbenbiihren,  Westphalia,  202.  Greenland, 
L'nj-205.  Assuk,  203.  Ovifak,  203,  204.  Pfaff-Oberg,  204,  205.  General 
Structure  of  the  Meteoric  Basalts,  205  ;  not  fragmeutal,  205.  Nomenclature, 
205.  Future  changes,  206. 

SECTION   II. 
THK  PSEUDO-METEORITES 20G-208 

Wutcrvillc,  Maine,  206,  207.  Richland,  South  Carolina,  207.  Igast,  Russia, 
207,  2<is.  Waterloo.  New  York,  208.  Concord,  New  Hampshire,  208.  Audc- 
sitc  type,  208. 


Xvi  CONTENTS. 

EXPLANATION  OF  THE  TABLES 209 

TABLES   OF   CHEMICAL   ANALYSES ii-xxxiii 

TABLE      I.     Analyses  of  Chromito  arid  Picotite ii_v 

TABLES   II.-V.  —  A  Classified  List  of  Complete  (Bauscli)  Analyses  of  Meteoric  and 

Terrestrial  Rocks. 

TABLE    II.     Siderolite vi-xv 

TABLE  III.     Pallasite xvi,  xvii 

TABLE  IV.     Peridotite xviii-xxxi 

TABLE   V.     Basalt,  Part  I.     The  Meteoric  Basalts        xxxii.  xxxiii 


The  black-faced  figures  in  the  text,  e.  g.  3001,  refer  to  the  numbers  of  specimens  in  the  Whitney 
Lithological  Collection  in  the  Museum  of  Comparative  Zoology. 

The  letters  A.  E.  prefixed,  and  G.  and  P.  affixed,  refer  respectively  to  special  collections,  belonging 
to  the  Whitney  Collection,  made  by  Mr.  Diller  in  the  Assos  Expedition,  Professor  W.  M.  Gabb  in 
San  Domingo,  and  Professor  W.  H.  Pettee  in  California  ;  e.  g.  A.  E.  324  ;  250  G.  ;  45  P. 


LITHOLOGICAL  STUDIES. 


CHAPTER    I. 

SECTION  I.  —  The  Structure  of  the  Earth. 

THE  "  natural  system  of  rocks  "  ought  to  contain  within  itself  a  key  to 
the  history  of  the  earth,  and  to  be  an  exponent  of  that  history.  The  entire 
physical  universe  seems  to  be  under  the  government  of  a  universal  law,  and 
our  classification  ought  to  accord  with  that  law,  so  far  as  it  has  been  ex- 
pressed in  the  rocks  themselves.  This  law  has  thus  far  been  best  formulated 
by  Sir  William  Thomson  as  the  degradation  and  dissipation  of  energy,  —  or,  as 
it  may  be  styled,  the  passage  from  the  unstable  towards  a  more  stable 
condition,  —  the  tendency  towards  harmony  with  the  environment.  This  I 
regard  as  the  law  under  which  the  universe  has  moved  from  its  beginning, 
and  under  which  it  will  continue  its  course  uniformly  towards  the  end, 
believing  that  no  turning  back  can  occur,  and  that  no  energy  once  lost 
can  be  restored  except  by  the  same  Almighty  Power  which  gave  it  birth.* 
It  is  in  accordance  with  this  law  that  I  have  tried  to  do  my  work,  and  to 
set  forth  the  principles  on  which  the  rocks  described  are  classified ;  in 
other  words,  this  is  an  attempt  to  explain  the  present  condition  of  the  rocks 
by  tracing  out  their  past  history. 

The  terms  "  lithology,"  "  petrography,"  and  "  petrology  "  are  so  indefi- 
nitely employed  that  it  seems  necessary  to  give  some  fixed  meaning  to  them 
here.  For  this  purpose  I  define  Lilln>Inf/>/  as  that  science  which  treats  of 
the  constitution  and  physical  structure  of  rocks.  It  corresponds  somewhat 
to  the  anatomy  and  histology  of  animals,  including  the  study  of  morbid 
tissues. 

»  Science,  1883,  i.  541. 
1 


2  THE  STRUCTURE  OF  THE  EARTH. 

Petrology  treats  of  the  origin,  history,  physical  features,  mode  of  occur 
rence,  and  relations  of  rock  masses. 

Lithology  is  essentially  an  in-door  or  cabinet  and  laboratory  science ;  while 
petrology  is  exclusively  a  field  study.  The  former  needs  for  its  pursuit  hand 
specimens  only;  for  the  latter  we  must  have  the  rocks  in  situ. 

Petrography  I  define  as  that  branch  of  science  which  embraces  both 
lithology  and  petrology.  It  includes  everything  that  pertains  to  the  origin, 
formation,  occurrence,  alteration,  history,  relations,  structure,  and  classifica- 
tion of  rocks  as  such.  It  is  the  essential  union  of  field  and  laboratory  study. 

So  far  as  possible  my  work  has  been  carried  on  according  to  petro- 
graphical  rather  than  ordinary  lithological  methods,  and  with  the  belief 
that  field  evidence  is  stronger  than  any  laboratory  evidence  can  be  in 
all  matters  relating  to  the  origin  of  rocks. 

The  facts  developed  by  petrographical  study  seem  to  me  to  demand  for 
their  explanation  a  former  liquid  condition  of  this  globe,  and  the  admission 
that  all  rocks,  not  of  organic  origin,  now  forming  a  portion  of  the  earth's 
crust,  are  the  results  either  of  that  molten  condition,  or  of  the  action  of 
atmospheric  and  hydrous  agencies  upon  the  formerly  liquid  material.  The 
belief  in  the  former  fluid  condition  is  in  accord  with  the  demands  of  geology 
and  the  results  of  physical  and  astronomical  research ;  for  it  seems  proper  to 
hold,  that,  as  is  the  present  physical  condition  of  the  nebula?,  stars,  sun, 
planets,  and  satellites,  so  was,  or  is,  or  will  be,  this  earth.  Indeed  the 
various  phenomena  with  which  we  are  concerned  seem  to  be  but  the  con- 
comitants and  results  of  the  passage  of  this  earth  from  its  active  condition, 
as  a  hot  fluid  mass,  towards  a  cold,  inert,  and  passive  state.  Is  it  not  our 
part  to  study  matter  in  its  present  transitory  stage,  and  from  the  facts  thus 
gathered  to  reconstruct  as  far  as  possible  its  past  history  and  infer  its  future 
course  ?  To  me  the  beginnings,  the  various  transitory  stages,  and  signs  of 
what  the  end  will  be,  are  apparent  in  the  rocks ;  and  the  effort  of  the  classi- 
fication here  employed  is  to  give  voice  to  these  changes,  or  to  the  unstable- 
ness  of  the  rock  constituents,  while  the  classifications  of  others  appear  in 
general  to  be  based  upon  the  assumed  stability  of  the  rock  constituents,  — 
that  is,  they  assume  that  as  the  rocks  now  are  so  they  were,  and  always 
will  be. 

I  am  unable  to  explain  the  facts  obtained  in  the  petrographical  study  of 
the  rocks  except  on  the  supposition  that  the  eruptive  rocks  of  all  kinds 
came  from  the  interior  part  of  the  earth,  and  from  below  the  sedimentary 


IS  THE  EARTH   A   SOLID   BODY?  3 

deposits ;  moreover  it  would  seern  that  they  must  come  from  a  portion  that 
has  either  never  solidified,  or  which  through  some  cause  has  been  reliquefied. 
Here,  then,  it  will  be  desirable  that  some  examination  should  be  made  of 
the  evidence  derived  from  physical  and  mathematical  laws  on  which  is  based 
the  opinion  held  by  many  that  the  earth  is  solid. 

This  evidence  may  be  considered  under  two  divisions.  1°.  That  derived 
from  the  phenomena  of  precession  and  nutation,  and  of  the  tides.  2°.  That 
derived  from  the  action  of  matter  under  the  combined  influence  of  heat  and 
pressure. 

In  the  first  case,  the  conclusions  which  have  been  reached  have  been 
obtained  by  assuming  certain  hypothetical  globes  with  a  certain  definite 
structure,  substituting  for  these  the  name  earth,  and  then  claiming  that  the 
conclusions  applied  to  the  actual  earth  instead  of  to  the  hypothetical  globes,  for 
which  the  name  earth  was  used  just  as  the  algebraist  uses  x  and  y.  Hop- 
kins assumed  for  his  globes:  1°,  a  homogeneous  fluid  mass  enclosed  in  a 
homogeneous  solid  shell ;  2°,  a  heterogeneous  fluid  mass  enclosed  in  a  hetero- 
geneous solid  shell.  The  transition  between  the  entire  solidity  of  the  shell 
and  the  perfect  fluidity  of  the  interior  mass  was  assumed  by  him  as  being 
an  abrupt  one.  He  further  assumed  that  the  circulation  would  go  on  in 
the  mass  until  it  lost  its  perfect  fluidity  in  every  part  at  nearly  the  same 
moment.* 

Sir  William  Thomson,  in  the  same  way,  drew  his  conclusions  from  globes 
assumed  to  have  a  thin  shell,  passing  abruptly  either  into  a  homogeneous 
incompressible  fluid,  mobile  like  water;  or  into  a  heterogeneous  viscid 
fluid  interior.! 

Likewise  Professor  George  H.  Darwin  has  taken  as  the  basis  for  his  dis- 
cussions, if  he  is  not  misunderstood,  homogeneous  spheroids  which  are  vis- 
cous and  non-elastic,  also  those  which  are  elastico-viscous,  and  those  which 
are  either  elastic,  plastic,  or  viscous.^ 

The  view  that  the  phenomena  of  precession  and  nutation  prove  the 
earth  to  be  solid  was  opposed  by  Hennessy,§  Delaunay, ||  Newcomb  and 

*  Philos.  Trans.,  1839,  pp.  381-423;  1840,  pp.  193-208  ;  1842,  pp.  43-55. 

t  Trans.  Koyal  Soc.  Edin.,1864,  xxiii.  157-169;  Plul.  Mag .,1803  (4),  xxv.  1-14,149-151;  Phil. 
Trans.,  lM',3,  ,,,,.  573-5S2;  Trans.  Geol.  Soc.  Glas.,  1878,  vj.  38-49;  Nat.  Phil.,  1867,  I.  670-727; 
Nature,  1S72,  v.  223-2:24,  257-259. 

\  Phil.  Tiaus.,  1SSO,  clxx.  1-35,447-593;   1882,  elxxii.  187-230. 

§  Phil.  Trans.,  1851,  pp.  495-517;  Nature,  1871,  iii.  420;  1872,  v.  288,  289;  Geol.  Mag.,  1871  (1), 
viii.  210-218. 

I!  («•(.!.  Ma-,  1868   (1),  v.  507-511. 


4  THE   STKUCTUREOF  THE  EAETH. 

others;  and  although  strongly  supported  by  Thomson  for  some  fourteen 
years  it  was  abandoned  by  him  in  1876,*  and  is  now  generally  given 
up. 

The  view  that  the  phenomena  of  the  tides  prove  the  earth  to  be  solid 
is  still  sustained  by  Thomson  and  Darwin,  but  their  conclusions  only  apply 
to  the  assumed  globes  and  not  to  the  earth  itself.  Their  conclusions  are  also 
opposed  by  Hennessy,  Fisher,  Airy,  and  many  others. 

The  difficulty  seems  to  be  that  it  is  beyond  the  power  of  any  known 
transcendental  mathematics  to  grasp  the  problem  of  the  earth's  structure,  if 
its  most  probable  condition  be  assumed.  This  condition  may  be  described 
as  being  that  of  a  globe  having  a  density  gradually  increasing  from  the 
exterior  inwards  towards  the  centre,  but  with  its  materials  heterogeneously 
arranged,  and  with  the  lighter  crust  gradually  and  irregularly  passing  into 
the  heavier  liquid  beneath. 

If  our  attention  be  now  turned  to  a  consideration  of  the  evidence  derived 
from  the  behavior  of  matter  under  the  combined  action  of  heat  and  pressure, 
which  behavior  is  said  to  prove  that  the  interior  of  the  earth  is  solid,  the 
important  questions  are :  1°.  What  are  the  materials  forming  the  earth's 
mass  ?  2°.  Do  these  expand  or  contract  on  passing  from  the  liquid  to  the 
solid  state  ? 

In  answer  to  the  first  question,  it  may  be  said  that  the  results  of  petro- 
graphical  study  render  it  probable  that  the  portion  of  the  interior  mass 
lying  nearest  the  centre,  and  concerning  which  we  have  any  data,  is  com- 
posed of  iron,t  either  wither  without  nickel.  As  we  recede  from  this  portion 
we  find  pyrrhotite  united  with  the  nickel  and  iron.  Then  these  minerals 
are  further  joined  with  olivine,  or  olivine  and  enstatite,  in  varying  propor- 
tions, until  a  region  is  reached  composed  almost  entirely  of  one  or  both  of 
these  silicates  with  or  without  diallage.  From  this  we  pass  into  the  common 
basaltic  rocks,  then  into  the  andesites,  and  so  on  outward  into  the  trachytic, 
rhyolitic,  and  jaspilite  forms.  However  true  this  order  may  have  been  for 
the  liquid  earth,  it  is  certain  that  in  the  solid  portions  of  the  crust  these 
materials  are  interlaced  now  with  each  other  in  every  conceivable  way,  and 
that  in  the  chemical  and  sedimentary  deposits  they  have  been  intimately 
mingled.  As  to  what  may  be  the  composition  of  the  earth's  mass  nearer 
the  centre,  if  there  be  anything  there  besides  the  iron  and  nickel,  we  have 

*  Report  Brit.  Assoc.  1876,  xlvi.  (sect.)  1-12. 

f  Whitney's  Metallic  Wealth  of  the  United  Slates,  1354,  p.  434.     Judd's  Volcanoes,  1SS1,  pp.  307-324. 


THEORIES   OF   THE   EARTH'S   SOLIDIFICATION.  5 

no  clew,  unless  it  be  that  very  possibly  some  of  the  rarer  elements  now  found 
mixed  with  the  iron  may  occur  there. 

It  was  claimed  by  Sir  William  Thomson*  that  the  earth  must  have 
solidified  from  the  centre  outward  in  accordance  with  the  "  thermo-dynamic 
law  "  of  his  brother  Professor  James  Thomson,  which  may  be  stated  in  these 
words:  All  material*  which  contract  on  congelation  Iiave  their  melting  point  rained  b/j 
i;  ivliile  bodies  which  expand  on  freezing  Jiavc  their  melting  point  lowered  by 
Thomson,  in  common  with  nearly  all  physicists,  held  that  the  ex- 
pansion of  water  and  that  of  bismuth  on  freezing,  were  exceptional  cases ; 
but  that  contraction  was  the  rule,  and  that  pressure  would  therefore  over- 
come the  increment  of  heat  as  the  centre  was  approached.  The  mistake 
made  here  was,  that  the  cold  solid  was  compared  with  the  hot  liquid ;  the 
fact  being  overlooked  that  this  law  applies  to  the  point  of  passage  from  the 
liquid  to  the  solid,  and  not  to  the  relative  density  of  the  two  taken  at  tem- 
peratures differing  hundreds  and  even  thousands  of  degrees. 

Experiments  t  by  Mallet,  Centner,  Millar,  Whitley,  Hannay,  Anderson, 
Nies,  Wiukelmann,  and  Wrightson  show  that  in  the  case  of  steel,  iron,  tin, 
copper,  zinc,  bismuth,  antimony,  etc.,  compared,  at  a  temperature  just  below 
the  melting  point,  with  the  melted  material  at  about  its  freezing  point,  the 
solid  is  the  lighter ;  but  that  these  metals  contract  so  on  cooling  that  when 
cold  all,  except  bismuth,  are  then  heavier.  It  would  seem  that  if  solids 
and  liquids  are  compared  together  at  about  the  temperature  of  their  con- 
gelation the  solid  is  the  lighter ;  and  that  therefore  the  pressure  at  the 
earth's  interior  would  cause  these  metals  to  remain  liquid  at  a  lower  tem- 
perature than  they  would  on  the  earth's  surface. 

The  same  law  holds  good  for  slag,  and  seems  to  do  so  for  lava ;  in  fact 
this  is  probably  true  of  almost  all  rocks,  although  the  evidence  is  far  from 
being  conclusive. 

Experiments  J  made  by  Hopkins,  Bunsen,  Mousson  and  others  indicate 
that  to  change  the  fusion  point  a  few  degrees  an  enormous  pressure  is 
required,  and  that  the  law  of  Thomson  is  really  capricious  and  variable,  if 
always  true.  Hence,  so  far  as  our  knowledge  extends  in  regard  to  the 

*  Traus.  Geol.  Soc.  Glasgow,  1878,  vi.  38-49. 

t  Pn.c.  Hoy.  Soc.,  1874,  xxii.  3G6-3G8  ;  1875,  xxiii.  209-234;  Nature,  1874,  x.  156,  157;  1S77,  xr. 
520,  530;  xvi.  23,  21;  1878,  xviii.  397,  398,  464;  Proc.  Roy.  Soc.  Edin.,  1879,  x.  359-362;  Silz.  Akad. 
Miincliuu,  1881,  pp.  03-112;  1'liil.  Mag.,  l^sl,  (.")),  xi.  295-299. 

}  Report  Brit.  Assoc.,  1S54,  xxiv.  (sect.)  57,  58;  Ann.  Pliysik  Chcmic,  1850,  Ixxxi.  502-567;  1S58, 
cv.  101-174;  Everett's  iVsduuuul's  -\;it.  Mill.,  1872,  pp:  312,  313;  1883,  pp.  331,  332. 


6  THE  STRUCTUEE  OF  THE  EARTH. 

action  of  matter  under  pressure  and  heat,  there  is  fur  more  reason  for 
believing  the  earth  to  be  liquid  than  for  taking  the  opposite  view. 

From  what  has  here  been  stated  it  would  seem  that  there  is  no  evidence 
drawn  from  mathematical  and  physical  laws  which  obliges  the  petrographer 
and  geologist  to  assume  an  interior  structure  for  the  earth  different  from 
that  which  the  facts  of  geology  and  petrography  would  lead  them  to  expect.* 

Starting,  then,  with  the  accepted  belief  that  this  earth  was  once  an 
intensely  hot  gaseous  body,  it  follows  that  if  the  heavier  gases  tend  to 
lie  nearer  the  centre  than  the  lighter  ones,  the  dissipation  of  heat  could 
only  take  place  through  the  slow  conductivity  of  gases.  In  like  man- 
ner, when  the  earth  cooled  down  to  a  liquid  mass  convection  would  soon 
cease,  if  it  ever  existed,  on  account  of  the  different  densities  of  the  earth's 
materials ;  and  here  also  the  dissipation  of  heat  would  have  to  take  place  by 
the  slow  conduction  of  liquids.  In  the  same  way,  in  the  solid  portions  of  the 
earth  the  heat  from  the  interior  has  to  be  conveyed  outwards  through  broken, 
fissured,  heterogeneous  material.  It  would  seem  that  all  these  conditions 
should  be  taken  into  account  in  all  physical  discussions  of  the  age  of  the 
earth  and  sun ;  but  thus  far  all  calculations  seem  to  have  been  based  upon 
the  laws  of  the  relation  of  gases  and  liquids  of  about  the  same  density. 
There  should  further  be  considered  the  heat  disengaged  by  the  chemical 
unions  necessary  to  form  the  present  mineral  combinations  now  existent  on 
the  earth. 

As  the  liquid  earth  cooled  and  its  materials  grew  viscous,  all  interchange 
of  materials  would  be  retarded;  and  as  the  cooling  continued,  the  lighter 
exterior  liquid  portion  would  form  a  hot  crust,  which  would  be  lighter  than 
the  underlying  liquid.  On  account  of  the  viscous  condition  through  which 
the  earth's  materials  must  pass  before  solidification,  the  crust  would  gradu- 
ally shade  into  the  underlying  liquid,  and  both  would  be  nearly  in  the  same 
condition  with  each  other  as  to  temperature.  It  is  not  probable  that  the 
crust  would  break  xip  and  begin  to  sink,  because,  even  if  its  surface  grew 
cold,  it  would  always  have  this  hot  solid  base  lighter  than  the  underlying 
viscous  liquid,  which,  owing  to  the  increase  of  specific  gravity  as  the  in- 
terior is  approached,  would  probably  be  more  dense  than  any  of  the  over- 
lying cold  crust.  Even  if  the  crust  should  become  heavier,  break  up,  and 
begin  to  sink,  this  sinking  would  be  very  slow,  on  account  of  the  viscosity 

*  Whitney,  Earthquakes,  Volcanoes,  and  Mountain  Buildiug,  1871,  p.  74;  Daua,   Man.  Gcb].,   18SO, 
p.  812. 


THE   PltOHABLE   CONDITION   OF   THE   EARTH'S   INTERIOR.  7 

of  the  liquid,  and  its  constantly  increasing  density  ;  while  the  heat  imparted 
to  the  sinking  material  would  tend  to  bring  it  to  about  the  same  specific 
gravity  with  the  liquid  portion  as  the  sinking  mass  neared  its  melting  point. 
But — what  is  of  still  greater  importance  —  the  sinking  material  would 
FOOII  reach  a  liquid  of  different  composition  and  greater  density  than  the 
crust;  and  farther  than  this  it  could  not  sink.  That  sinking  of  the  crust 
to  the  centre,  which  Sir  William  Thomson  supposed  would  take  place,  could 
only  do  so  in  case  the  hot  solid  was  heavier  than  the  liquid  interior,  and 
that  liquid  homogeneous.  But  both  these  conditions  appear  opposed  to 
what  we  know  of  the  properties  of  matter  and  of  the  heterogeneous  com- 
position of  the  earth. 

The  structure  of  the  earth  that  would  naturally  follow,  from  what  has 
been  above  stated,  would  be  a  heterogeneous  crust  floating  on  a  denser 
heterogeneous  liquid,  and  one  which  the  interior  pressure  tends  to  keep 
liquid  at  a  lower  temperature  than  on  the  surface,  so  far  as  it  affects  it 
at  all. 

In  an  earth  like  this,  owing  to  the  gradual  passage  of  the  crust  into  the 
viscous  liquid  interior,  no  shrinking  of  the  nucleus  from  the  exterior  could 
take  place,  but  the  earth  would  contract  as  a  whole.  A  linear  shortening 
of  the  crust  would  occur  that  would  crush  it  together,  and  cause  its  depres- 
sion in  some  places  and  its  elevation  in  others.  The  depression  of  any  por- 
tion of  the  crust  into  the  liquid  interior  would  naturally  cause  an  equivalent 
weight  of  the  heavier  liquid  to  rise,  and  perhaps  overflow.  This  simple 
sinking  of  a  portion  of  the  crust  on  one  side  with  its  corresponding  but  less 
elevation  on  the  other,  with  the  attendant  fissuring,  would  afford  all 
the  dynamic  agencies  needed  to  raise  lavas  to  the  tops  of  our  highest 
mountains,  and  would  account  for  the  association  of  volcanoes  with  de- 
pressed basins,  for  fissure  eruptions,  etc.*  The  contraction  could  hardly 
be  expected  to  be  equal  in  every  portion,  while  the  depression  of  portions 
of  the  crust  with  the  attendant  outflows  would  cause  an  unequal  thickness 
of  the  crust,  with  great  irregularities  in  its  base  adjacent  to  the  liquid  in- 
terior. The  outflows,  themselves,  would  cause  this  crust  to  be  tied  through 
and  through  by  the  different  eruptive  materials. 

This  great  irregularity  in  thickness,  which  the  earth's  crust  is  supposed 
to  present, .coupled  with  the  viscosity  of  its  interior  portion  next  the  crust, 
\\oald  apparently  prevent  any  direct  or  special  connection  between  different 

*  Whitney,  Earthquakes,  Volcanoes,  and  Mountain-Building,  p.  90. 


8  THE   ORIGIN   AND   ALTERATION   OF   ROCKS. 

vents,  even  if  they  were  near  one  another.  The  viscidity  of  the  cooling 
liquid  portion  would,  of  itself,  prevent  any  rapid  flow  of  material  from  one 
point  to  another.  But  at  the  same  time  the  liquidity  of  the  interior  mass 
would  cause  it  to  seek  escape  from  pressure  at  any  available  opening,  how- 
ever far  that  vent  might  be  from  the  point  of  pressure.  Yet  the  more 
viscous  the  material,  the  less  applicable  would  be  the  ordinary  law  of  the 
transmission  of  pressures  by  liquids. 

The  part  played  by  water  in  a  volcanic  eruption  seems  to  consist  mainly 
of  its  action  on  the  lava  during  its  passage  upwards,  instead  of  serving  as 
the  cause  or  primitm  mobile  of  the  eruption.  It  is  difficult  to  see  how  lava 
in  ascending  to  the  earth's  surface'  could  reach  it  without  meeting  water 
somewhere  on  its  way.  This. water  with  its  attendant  phenomena  seems  to 
be  the  accident,  rather  than  the  cause  of  the  eruption.  As  stated  before,  a 
different  view  of  the  present  structure  of  the  earth's  interior  can  be  taken, 
which  may  not  be  inconsistent  with  the  facts  of  petrography.  This  is  that 
the  interior,  or  at  least  the  portion  from  which  our  eruptive  rocks  come,  is 
solid,  but  in  such  a  state  that  it  can  be  readily  reliquefied.  This  reliquefac- 
tion  may  be  brought  about  either  from  increase  or  diminution  of  pressure, 
according  as  future  experiments  may  show  the  relative  densities  of  hot 
solid  and  liquid  matter  to  be.  The  supposition  that  eruptive  rocks  come 
from  these  re-fused  portions  of  the  earth's  originally  solidified  primitive 
material,  would  perhaps  explain  the  origin  of  the  minerals  of  the  first  or 
foreign  class,  to  be  spoken  of  later,  which  occur  in  these  rocks. 

SECTION  II.  —  The  Origin  and  Alteration  of  Rocks. 

THE  theory  of  the  origin  of  rocks  generally  taught  in  America  is  the 
following,  with  some  more  or  less  important  modifications :  The  sedimentary 
(chemical  and  mechanical)  rocks  derived  from  the  ruins  of  the  "primeval 
crust"  form  all  that  portion  of  the  earth's  crust  which  is  now  known.  By 
ordinary  denudation  these  rocks  would  be  removed  from  one  point  and  depo- 
sited in  another  locality,  the  result  being  that  the  underlying  sediments  would 
be  still  more  deeply  buried  in  one  place,  and  exhumed  in  another.  The  por- 
tions thus  more  deeply  buried  would  be  invaded  by  the  earth's  central  heat, 
this  giving  rise  to  a  more  or  less  intense  chemical  action  in  them.  The  seat 
of  this  action  is  known  as  the  "  zone  of  aqueo-igneous  fusion  "  (solution),  and 
all  sediments,  if  sufficiently  deeply  buried,  come  within  this  hypothetical 


Til  KOI! IKS  AT  I'RKSKNT  IX  VOGUE.  9 

/one.  The  different  ])ortions  of  (lie  sediments  would  be  more  or  less  affected 
ami  metamorphosed,  according  to  their  chemical  constitution,  and  their  prox- 
imity to  the  hypothetical  zone.  If  they  came  within  the  zone,  their  fusion 
or  solution  would  give  rise  to  lavas  and  volcanic  eruptions.  Some  authors 
hold  that  every  form  of  eruptive  rock  comes  from  sedimentary  materials 
which  have  been  thus  acted  upon;  while  others  maintain  that,  although  the 
true  lavas  and  intrusive  rocks  may  have  been  derived  from  non-sedimen- 
tary material,  yet  the  sedimentary  rocks  take  upon  themselves  forms  undis- 
tingnishable  from  those  of  the  volcanic  rocks.  Other  modifications  of  this 
theory  are  delegating  the  source  of  the  eruptive  rocks  to  re-fused  portions 
of  the  original  solidified  crust  of  the  earth,  which  has  been  fused  again  on 
account  of  relief  from  pressure  by  denudation.  This  last  view  has  been 
founded,  so  far  as  present  evidence  shows,  on  a  misconception  of  the  apparent 
general  action  of  matter  in  passing  from  a  liquid  to  a  solid  (not  cold)  state; 
therefore  this  should  be  abandoned,  and  fusion  by  increase  of  pressure  either 
through  the  earth's  contraction  or  by  the  deposition  of  sediments  substi- 
tuted. Another  theoretical  view  is  simply  a  remodelling  of  the  old  Werne- 
rian  hypothesis,  and  its  application  to  the  crystalline  rocks.  According  to 
this  view  we  are  taught  that  all  these  rocks  were  deposited  in  pre-Cambrian 
time,  and  that  all  eruptive  rocks  have  been  derived  from  these  chemical  ones 
by  aqueo-igneous  solution  or  fusion.  These  crystalline  rocks  and  their 
derived  eruptive  forms  are  then  divided  according  to  their  lithological 
characters  into  distinct  geological  ages,  and  their  age  is  said  to  be  recogniz- 
able whether  the  rocks  themselves  be  seen  in  their  original  form  or  in  that 
of  dikes  and  lava-llo\vs. 

If  the  above  views  are  correct,  we  should  expect  to  find  in  some  form- 
ations rocks  which  had  suffered  every  degree  of  alteration,  the  same  rock 
passing  from  an  unmetamorphosed  condition  into  a  highly  metamorphosed  or 
even  eruptive  one,  with  every  gradation  between.  At  certain  points,  when 
denudation  has  succeeded  a  former  epoch  of  accumulation,  the  more  or  less 
deeply  buried  sediments  would  again  appear  upon  the  surface,  showing 
greater  or  less  evidence  of  the  conditions  to  which  they  had  been  subjected. 
l»y  carefully  selecting  the  localities  to  be  studied,  we  naturally  should  ex- 
pect to  find  every  degree  of  change  in  the  rocks,  and  various  transitions  by 
direct  passage  from  rocks  unmistakably  sedimentary  into  those  that  are 
truly  eruptive,  in  their  present  position,  —  from  those  rocks  whose  original 
iragmental  structure  is  undoubted,  to  those  that  have  been  in  a  plastic, 

2 


10  THE   ORIGIN  AND  ALTERATION   OF   EOCKS. 

semi-fluidal,  or  fluidal  state.  All  these  changes  should  exist  in  the  same 
continuous  mass  of  rock,  and  we  ought  to  be  able  to  trace  the  gradations 
from  one  place  to  another.  That  such  passages  have  been  observed,  has 
been  repeatedly  claimed,  but  when  the  localities  where  these  facts  could 
be  observed  were  sought  for,  they  could  not  be  found. 

The  results  of  petrographical  study  seem  to  point  to  the  following  as  the 
probable  origin  of  rocks.  If  we  start  from  a  cooling  liquid  earth  then  all 
mechanically  and  chemically  formed  rocks  have  come  from  the  liquid  ma- 
terial originally.  Furthermore,  all  the  eruptive  rocks  appear  to  have  come 
from  below  the  sedimentary  ones,  and  are  only  influenced  by  them  in  their 
composition,  by  the  materials  accidentally  picked  up  during  their  passage 
through,  or  flow  over  the  latter.  In  the  case  of  volcanic  rocks,  we  should 
expect  to  have  associated  with  the  lava,  ashes,  and  in  fact  every  kind  of 
material  projected  from  the  crater,  including  debris  and  inud.  All  these 
would  be  naturally  more  or  less  intimately  mixed  together  according  as  one 
was  deposited  on,  or  around  the  other,  —  or  as  one  in  its  flow  picked  up,  sur- 
rounded, or  overlaid  another.  This  would  associate  all  loose  materials  and 
rocks  of  any  kind  that  existed  in  the  locality  prior  to  the  lava  flow ;  while 
during  that  time  and  later  the  atmospheric  agencies  would  tend  to  still  more 
intimately  mingle  these  diverse  materials,  and  obliterate  their  differences. 
Wherever  the  lava  was  exposed  to  detntal  action,  there  would  be  deposited 
about  and  around  it  detritus  of  the  same  material,  mixed  or  not,  as  the  case 
might  be,  with  that  from  other  rocks,  —  especially  if  the  eruption  took  place 
on  or  near  the  shore  line.  In  the  case  of  massive  or  fissure  eruptions  and 
dikes,  we  should  expect  but  few  or  none  of  the  common  accompaniments  of 
an  ordinary  explosive  volcanic  eruption,  but  all  eruptive  material  would  be 
subject  to  degradation,  and  would  under  proper  conditions  become  associated 
with  its  own  detritus  and  that  formed  from  other  rocks.  All  the  associated 
detritus,  if  of  one  kind,  would  suffer  the  same  alterations  which  non-frag- 
mental  material  of  the  same  kind  has  to  pass  through.  Under  conditions 
otherwise  identical,  detrital  material  would  doubtless  be  affected  in  a  greater 
degree  than  the  solid  rock,  owing  to  the  former's  greater  perviousness  to 
water.  While  in  the  unaltered  condition  we  may  be  able  to  readily  distin- 
guish the  fragmentnl  from  the  non-fragmental  forms  by  the  unaided  eye,  this 
is  no  longer  possible  when  both  have  been  subject  to  alteration.  They  then 
closely  simulate  one  another,  and  the  microscope  used  in  connection  with 
the  field  evidence  offers  the  only  means  of  distinguishing  the  fragmentul 


K\  \MIXATION  OF  CURRENT  THEORIES.  11 

from  the  non-fragnicntal  form.  When  rooks  of  more  than  one  kind  are 
mixed  in  the  detritus,  the  alteration  and  appearance  of  the  sedimentary  rock 
formed  from  this  undergoes  a  corresponding  modification. 

We  should  expect  to  find  certain  very  intimate  relations  between  all 
these  various  forms  of  associated  rock,  and  it  would  be  very  difficult  to  dis- 
tinguish, in  the  older  and  more  altered  forms,  between  the  material  picked 
up  during  the  flow,  the  ashes  or  debris,  and  the  solid  non-fragmental  rock. 
The  greater  the  amount  of  secondary  alteration  which  these  different  rocks 
have  sull'ered,  the  greater  the  difficulty  of  distinguishing  between  them.  In 
no  case,  however,  would  the  fragrnental  pass  into  the  non-fragmental  form 
by  insensible  gradations  or  otherwise.  It  is  true  that  they  sometimes  appear 
to  do  so,  but  that  appearance  is  only  superficial. 

In  order  then  to  decide  between  the  different  theories  proposed  for  the 
origin  of  eruptive  rocks,  it  is  necessary  to  make  some  examination  of  the 
evidence  offered  in  their  support  by  petrographical  study.  For  this  pur- 
pose the  most  important  question  is,  do  sedimentary  rocks  take  upon  them- 
selves the  characters  of  eruptive  ones  ?  In  the  writer's  studies  he  has  found 
a  certain  resemblance  between  both  classes  of  rocks  when  they  are  of  similar 
composition.  This  is,  however,  only  in  the  case  of  rocks  greatly  altered,  and 
arises  from  secondary  changes  in  each ;  which  result  in  the  production  of 
new  mineral  constituents,  and  in  the  obliteration  of  the  original  structure 
of  both  to  a  greater  or  less  extent.  Indeed,  in  some  cases,  this  obliteration 
is  total,  the  minerals  and  mineral  characters  —  in  fact  .ill  the  characters  — 
of  the  rocks  thus  changed  being  rendered  unlike  those  which  belonged  to 
the  original  eruptive  rock.  These  alterations  are  apparently  more  depend- 
ent upon  the  chemical  composition  of  the  rocks,  and  the  conditions  to  which 
they  have  been  subjected,  than  upon  their  having  been  in  a  fragmental  or 
non-fragmental  state.  The  result  is,  that  the  eruptive  rock  is  degraded  to 
the  status  of  an  altered  sedimentary  rock,  not  that  the  latter  takes  upon 
itself  the  characters  of  an  eruptive  one.  Whether  the  two  classes  thus 
indicated  can  or  cannot  always  be  distinguished  under  the  microscope  in 
cases  of  extreme  alteration,  is  a  problem  of  the  future,  and  perhaps  the 
most  difficult  one  with  which  the  petrographer  will  be  confronted. 

Undoubtedly,  a  careful  study  of  the  field  relations  of  rocks  would,  in  the 
majority  of  cases,  suffice  to  settle  the  question  of  their  origin. 

If  sedimentary  rocks  should  be  found  under  peculiar  and  abnormal  con- 
ditions, to  present  the  characters  regarded  as  typical  of  eruptive  forms* 

•  Metamorpliism  produced  by  the  burning  of  Lignite  Beds  in  Dakota  and  Montana  Territories.    By  J.  A. 
Allen.     Proc.  Bost.  Soc.  Nat.  Hist.,  1874,  xvi.  240-262. 


12  THE   ORIGIN   AND   ALTERATION   OF   ROCKS. 

this  would  not  be  a  basis  for  assuming  that  normally  sedimentary  rocks  take 
these  characters ;  although  this  statement  is  one  which  is  frequently  made. 

Examinations  have  been  repeatedly  made  by  the  writer  for  the  purpose 
of  ascertaining  whether  any  rocks  whose  sedimentary  origin  was  undoubted 
had  acquired  the  microscopical  characters  of  eruptive  forms,  but  nothing  of 
the  kind  has  yet  been  discovered  by  him. 

In  order  to  prove  the  passage  of  a  sedimentary  rock  into  an  eruptive  one, 
it  is  necessary  to  have  on  one  side  the  undisputed  fragmental  form,  and  to 
trace  it  directly  by  continuous  passage  into  the  non-fragmental  one.  Not  an 
inch  of  the  parts  lying  between  should  be  allowed  to  escape  examination ; 
and  it  must  be  positively  known  that  no  line  of  junction  exists,  but  that  the 
two  rocks  form  a  continuous  whole.  In  no  case  on  record,  however,  does  it 
appear  that  passages  of  the  kind  indicated,  and  which  have  been  claimed  as 
existing,  have  ever  been  subjected  to  so  close  an  examination  as  is  here 
demanded.  Eruptive  and  sedimentary  rocks  at  their  line  of  junction  usually 
mutually  influence  one  another,  often  appearing  very  much  alike,  especially 
when  they  have  been  subjected  to  later  alterations  by  which  both  have  been 
affected.  It  is,  then,  to  be  expected  that  the  observer  who  is  not  practically 
familiar  with  these  occurrences  will  pass  directly  over  the  lines  of  junction, 
especially  if  he  has  been  taught  that  direct  passages  of  one  rock  into  another 
may  occur.  His  evidence  is  of  that  negative  kind  which,  for  various  reasons, 
can  usually  be  obtained  with  ease.  The  evidence  that  the  two  rocks  do  not 
pass  into  one  another  is  of  the  positive  kind,  for  the  line  of  junction  when 
once  seen  can  be  examined  and  re-examined  at  any  time ;  while  hand  speci- 
mens can  frequently  be  procured  which  will  show  both  kinds  of  rock  and  their 
junction  in  one  fragment.  We  can  then  have  positive  field  and  laboratory 
(including  microscopic)  evidence  that  the  two  rocks  are  not  the  same  but 
different  ones.  The  writer  has  had  frequent  occasion  to  examine  localities 
in  which  the  direct  passage  of  a  fragmental  rock  into  a  non-fragmental  one 
was  said  to  occur,  and  in  no  case  has  he  not  been  able  to  obtain  positive 
evidence  that  such  passage  did  not  exist,  when  the  conditions  were  such  that 
a  satisfactory  examination  could  be  made.  When  the  evidence  was  lacking 
it  was  always  owing  to  the  junction  being  covered,  or  else  shattered  by 
jointing,  frost,  etc. 

Practically,  when  the  existence  of  these  junctions  had  been  shown,  the 
observers  who  had  previously  denied  their  existence  have  always  said  : 
"That  is  not  a  typical  locality;  we  were  not  quite  sure  about  that  place, 


ORIGIN  OF  VOLCANIC  ROCKS  DISCUSSED.  13 

but  if  you  will  go  to  such  or  such  a  locality,  —  indicating  some  new  one, — 
you  will  find  an  undoubted  passage  of  the  sedimentary  rock  into  eruptive 
Ibrms."  \Vlicii  this  new  locality  is  also  examined  and  the  statements  are 
found  to  be  erroneous,  another  one  is  mentioned,  and  so  on;  until  one  must 
demand  hereafter  of  these  observers  that  they  shall  select  some  locality  on 
which  they  shall  be  willing  to  fully  and  finally  stake  their  pet  hypothesis, 
and  abide-  by  the  evidence. 

It  has  been  claimed  that  the  results  of  chemical  analysis  show  that  vol- 
canic rocks  are  derived  from  sedimentary  ones.  While  it  is  true  that  the 
former  have  a  composition  chemically  like  some  of  the  latter,  this  resem- 
blance is  easily  explained  by  the  fact  that  a  sedimentary  rock  ought  to 
resemble  chemically  the  massive  rock  from  whose  destruction  it  came.  The 
chief  difference  between  them  would  be  that  resulting  from  the  change 
brought  about  by  outside  influences,  the  introduction  of  foreign  material, 
etc.  Hence  the  chemical  resemblance  between  the  two  classes  of  rocks 
can  naturally  and  readily  be  explained  by  the  derivation  of  the  sedimentary 
from  the  eruptive  rocks ;  .and  there  is  no  need  to  resort  to  the  unnatural  and 
hypothetical  derivation  of  the  volcanic  from  the  sedimentary  rocks.  The 
former  derivation  is  the  one  seen  to  take  place  every  day,  while  the  latter 
is  unproved  as  yet,  and  those  who  hold  it  are  apparently  looking  at  the 
effect,  and  making  it  the  cause.  In  other  words,  it  seems  to  the  writer  that 
these  observers  have  taken  hold  of  the  subject  at  the  wrong  end. 

In  examining  the  products  of  volcanoes,  certain  minerals  appear  to  be 
characteristic  of  them,  which  are  of  prior  origin  to  the  consolidation  of  the 
lava.  These  minerals  show  evidence  that  a  hot  magma  has  directly  acted 
upon  them,  and  every  gradation  can  frequently  be  seen  between  the  almost 
untouched  mineral,  and  the  nearly  destroyed  one. 

I  regard  these  minerals,  unless  they  were  caught  up  by  the  lava  during 
its  passage  from  the  earth's  interior  to  its  surface,  as  evidences  that  the 
material  from  which  the  lava  was  derived  is  no  longer  in  its  original  con- 
dition, although  this  condition  was  not  like  that  of  any  of  our  sedimentary 
rocks.  Certain  of  these  minerals  are  easily  destroyed  ;  two  at  least,  suffer- 
ing alteration  readily  on  exposure,  and  it  seems  impossible  that  they  could 
survive  when  the  much  less  perishable  materials  of  our  sedimentary  rocks 
have  been  entirely  obliterated,  if,  as  is  supposed  by  many,  they  were  ever 
there.  These  minerals  are  unlike,  either  in  species,  variety,  or  form,  with 
possibly  a  few  exceptions,  any  minerals  occurring  in  sedimentary  rocks  as  a 


14  THE   ORIGIN  AND   ALTERATION   OF   ROCKS. 

metamorphic  product,  i.  e.,  not  derived  directly  from  the  eruptive  rocks. 
These  minerals  are  characteristic  not  only  of  the  modern  lavas,  but  also 
of  the  most  ancient  eruptive  rocks  in  which  secondary  alteration  has  not 
obliterated  their  characters ;  not  only  in  the  modern  basalt,  but  also  in  the 
ancient  melaphyr;  not  only  in  the  modern  rhyolite,  but  also  in  the  ancient 
felsite.  These  characters  are  not  confined  to  any  single  locality  or  age,  but 
are,  so  far  as  known,  world  wide,  and  go  back  to  the  earliest  times  in  which 
such  rocks  occur.* 

We  should  then  claim  that  the  field  evidence,  as  well  as  the  microscopic, 
is  opposed  in  toto  to  the  prevailing  theory  that  the  eruptive  rocks  are  derived 
from  sedimentary  ones.  That  theory  demands  immense  duration  of  time, 
unstable  continents,  enormous  forces,  a  solid  earth  that  shall  be  more  rigid 
than  glass,  and  yet  yield  like  a  rubber  ball  to  the  slightest  pressure  of  sedi- 
ments, lava  flows,  or  glaciers.  The  theory  in  question  demands  the  removal 
of  immense  masses  from  one  place,  and  their  deposition  in  another,  the  ele- 
vation of  billions  of  tons  in  order  to  avoid  the  necessity  of  admitting  the 
elevation  of  hundreds,  —  for  in  order  to  have  denudation  that  shall  bring 
once  deeply  buried  sediments  to  the  surface,  the  entire  mass  must  be  lifted 
bodily  above  the  surrounding  region,  or  from  the  zone  of  aqueo-igneous 
fusion  to  the  outer  air.  Which  view  requires  the  greatest  force  —  to  elevate 
and  depress  such  enormous  bulks  in  a  solid  earth,  or  to  raise  our  lavas  from  a 
liquid  interior  —  is  plainly  evident.  This  theory  requires  that  volcanic  action 
should  be  of  modern  birth  —  Tertiary  —  and  that  eruptive  rocks  of  earlier 
date  should  have  been  produced  by  different  forces  —  a  view  now  known  to 
be  false.  To  the  theory  that  the  crystalline  rocks  are  chemical  precipitates 
arranged  in  regular  succession,  there  arises  the  serious  objection  that  the 
oldest  form  —  the  so-called  Laurentian  —  is  cut  by  dikes  of  rocks  which, 
according  to  that  theory,  could  not  have  existed  below  them ;  that  is,  they 
belong  lithologically  to  the  so-called  Huronian  and  Norian  systems. 

In  contradistinction  to  the  views  here  indicated,  the  writer's  petrographical 
studies  lead  him  to  hold,  with  some  others,  that  all  volcanic  or  eruptive 
action  arises  from  the  original  igneous  state  of  the  earth  —  that  it  must  have 
begun  in  the  earliest  ages  of  this  globe.  This  action  being  a  manifestation 
of  a  dying  energy,  must  have  been  more  active  in  the  past  than  at  present, 
although  it  may  have  been  intermittent  in  character  as  all  such  forces  seem 
to  be.  The  products  of  this  action  have  been  the  same  from  the  earliest  to 

*  See  also  David  Forbes.     Nature,  1870,  ii.  283-286  ;  1873,  vii.  259-261. 


HOW  AND  \\1IKX  ALTERATION  TAKES  PLACE.  15 

the  latest  geological  periods ;  that  is,  a  rhyolite,  a  trachyte,  an  andesite,  or 
a  basalt  of  the  Azoic  or  Palaeozoic  times,  was  the  same  when  erupted  as  is 
the  rhyolite,  trachyte,  andesite  or  basalt  of  the  present  day,  or  of  the  Ter- 
tiary age.  The  difference  at  present  existing  between  these  ancient  and 
modern  forms  —  as  the  writer  believes  —  is  due  to  the  greater  alteration 
which  the  former  have  suffered ;  although  possibly,  a  difference  in  the  depth, 
or  some  peculiar  condition  prevailing  at  the  time  of  the  consolidation  of  the 
rock,  may  have  had  some  influence  in  causing  these  differences. 

Under  uniformly  like  conditions,  alteration  is  proportional  to  the  age,  in 
rocks  of  the  same  constitution  and  structure ;  but  when  rocks  of  like  char- 
acter are  subjected  to  the  same  agencies,  for  the  same  length  of  time,  like 
results  would  be  produced,  let  the  age  be  what  it  will.  The  original  crust 
and  the  eruptive  rocks  must,  then,  have  furnished  the  material  for  all  the 
other  rocks,  directly  or  indirectly,  except  such  as  was  derived  from  water 
and  the  atmosphere.  To  trace  these  changes,  and  to  follow  the  rocks  in  all 
their  variations  is  the  work  of  the  petrographer.  As  did  Cuvier  with  fossil 
l.oues,  so  may  the  lithologist  reconstruct  the  original  rock  from  the  fossil 
fragments  of  it  found  in  other  rocks.  The  presence  of  fragments  of  one  rock 
in  another,  however,  is  not  to  be  taken  as  proof  of  difference  of  geological 
age  between  them,  unless  it  can  be  proved  that  the  inclosed  rock  is  of  sedi- 
mentary origin.  A  lava  flow  on  a  sea-shore  would  have  its  fragments  in- 
cluded in  any  rock  then  forming,  and  this  would  hold  true  of  all  volcanic 
ejectments.  A  dike,  also,  passing  through  a  rock  forming  on  the  shore, 
would  have  all  materials  broken  from  it  inclosed  in  the  rock  then  forming, 
but  both  would  be  of  the  same  age  geologically,  although  differing  in  order 
of  time. 

In  studying  the  alterations  in  rocks  we  ought  not  to  confound  the  great 
molecular  changes  that  go  on  through  the  rock  mass  as  a  whole,  and  those 
changes  which  are  due  to  superficial  weathering.  The  latter  reproduce  to 
some  extent  the  characters  of  the  former,  but  go  to  greater  extremes,  caus- 
ing in  the  end  destruction  and  disintegration  of  the  rock  mass  itself.  The 
internal  changes  are  apparently  chemical  or  molecular  changes  in  the  whole 
rock  mass,  instead  of  simple  pseudomorphic  changes  of  single  minerals.  In 
no  sense  is  metamorphisin  to  be  looked  upon  as  extended  pseudomorphism  ; 
for  pseudomorphic  forms  are  but  an  accident  in  the  process  of  alteration,  and 
they  may  or  may  not  occur,  according  to  the  amount  of  that  alteration.  All 
the  changes  in  rocks  are  to  be  explained  by  taking  into  consideration  the 


16  THE   ORIGIN   AND   ALTERATION   OF   ROCKS. 

elements  of  the  entire  rock  mass,  and  all  elements  brought  into  it  by  the 
percolating  waters ;  the  chemical  reactions  taking  place  between  any  or  .ill 
of  these  elements  according  to  the  special  conditions,  and  not  being  confined 
to  simple  interchanges  between  the  constituents  of  two  minerals,  as  pseudo- 
morphs  in  mineral  veins  are  usually  explained.  The  failure  to  appreciate 
the  above  distinctions  is  believed  to  have  led  to  the  statement  of  much  that 
is  improbable  in  the  works  of  many  writers  on  pseudomorphic  and  metamor- 
phic  changes  in  rocks. 

When  we  consider  the  petrographical  structure  of  modern  volcanic 
districts  and  the  .alterations  their  rocks  have  undergone,  we  ought  not  to  be 
surprised  at  the  magnitude  of  the  changes  which  we  find  to  have  taken  place 
in  rocks  which  have  been  subjected  to  similar  conditions  during  countless 
ages.  But  these  changes  are  metamorphic,  and  the  rocks  thus  altered  are 
metamorphic  rocks.  Metamorphism,  however,  does  not  appear  to  be  lim- 
ited to  rocks  of  one  kind,  but  affects  all  classes.  The  amount  of  metamor- 
phism  any  rock  undergoes  under  the  same  conditions  seems  to  be  inversely 
proportional  to  the  amount  of  contained  silica ;  and  this  change  apparently 
began  as  soon  as  any  of  the  earth's  solid  material  was  exposed  to  the  com- 
bined action  of  air  and  water,  and  has  continued  up  to  the  present  day. 
Volcanic  or  eruptive  action,  including  a  subsequent  prolonged  exposure  to 
hot  water,  accompanying  the  dying  eruptive  force,  appears  to  have  been  an 
efficient  agent  in  metamorphism.  « 

According  to  the  above  view,  the  metamorphic  rocks  produced  would  be 
dependent  upon  their  chemical  composition  and  the  agency  by  which  the 
changes  were  effected,  but  would  not  be  at  all  dependent  upon  the  geolog- 
ical age.  Hence  lithological  characters  would  be  valueless  as  a  criterion 
for  determining  the  age  of  such  rocks. 

The  writer  finds  that  the  constituents  of  the  eruptive  rocks  and  their 
derivatives  pass  in  their  alteration  from  the  unstable  towards  more  stable 
compounds  in  the  conditions  to  which  they  are  subjected,  —  that  is,  they 
pass  into  forms  that  never  can  in  the  ordinary  course  of  nature  return  to 
their  original  condition.  In  this  there  exists  a  potent  factor  for  the  dissipa- 
tion of  energy.  The  potential  energy  of  the  original  chemical  combination 
is  in  a  greater  or  less  degree  lost,  and  cannot  be  restored  except  by  some 
foreign  power,  —  or,  in  other  words,  the  original  structure  and  composition 
cannot  be  normally  regained.  The  advocates  of  the  sedimentary  origin 
of  igneous  rocks,  however,  require  the  restoration  of  that  lost  energy,  and 


TIIKORIES  OF  ALTERATION  DISCUSSED.  17 

advocate  a  sort  of  perpetual  motion.  According  to  them  these  rocks  are 
born,  grow  old,  and  die,  and  their  remains  are  raised  again  and  again,  that 
the  process  may  be  repeated.  The  writer  accepts  the  birth,  old  age,  decay, 
and  death  ;  but  he  doubts  the  resurrection  and  believes  that  such  views 
are  opposed  to  physical  laws. 

A  crvstalline  structure  is  indigenous  in  any  eruptive  rock,  if  it  remains 
in  a  condition  that  allows  it  to  slowly  crystallize;  and  this  structure  is  not 
therefore  any  proof  of  great  age  in  a  rock,  or  a  sign  that  it  was  formed  at 
great  depth.* 

From  the  above  it  would  follow  that  such  rocks  as  the  felsites  cannot  be 
taken  as  characteristic  of  certain  ages  (Arvonian  or  Huronian) ;  but  if —  as 
the  writer,  with  others,  holds  —  they  are  old  rhyolites,  they  have  been  formed 
in  all  ages.  Again,  while  they  may  have  been  deeply  covered  with  detrital 
beds,  there  is  no  necessity  for  such  a  burial,  or  any  proof  that  they  were 
once  thus  covered,  any  more '  than  there  is  that  the  modern  rhyolites  have 
been. 

Also,  the  claim  for  long  times  for  the  formation  of  rocks  which  are  fine- 
grained and  fossiliferous  cannot  always  be  allowed  ;  as  for  instance,  the 
Florissant  shales,t  or  a  large  deposit  of  fine,  dust-like  powder,  observed  in 
the  vicinity  of  the  Black  Hills  by  my  colleague,  Mr.  Samuel  Garman.  This 
powder  is  made  up  of  minute  fragments  of  volcanic  glass,  forming  a  bed 
several  feet  in  thickness.  If  it  had  not  been  for  the  revelations  of  the 
microscope,  would  not  some  geologist  be  computing  the  number  of  thou- 
sands of  years  it  would  take  to  form  these  deposits  "  as  Nile  mud,"  when 
perhaps,  a  few  weeks  or  even  days  were  sufficient  for  this  purpose.  If 
the  deposits  in  question  had  been  subjected  to  sufficient  alteration  to 
obliterate  the  original  texture,  who  would  have  been  able  to  prove  the 
falsity  of  the  theory  of  a  slow  deposition  of  the  material  as  an  ordinary 
sediment? 

Another  illustration  is  afforded  by  the  Lake  Superior  sandstone,  which 
shows  that  extreme  care  is  required  to  ascertain  the  conditions  under  which 
any  deposit  formed,  before  the  length  of  time  required  for  its  formation  shall 
be  estimated,  t 

To  the  objections  offered  to  lavas  being  the  same  from  all  time,  on 
account  of  the  difficulty  of  believing  that  the  same  portions  of  the  earth's 

*  Bull.  Mus.  Comp.  Zool.,  1880,  vii.  111. 
f  Bull.  U.  S.  Geol.  Survey,  1881,  vi.  286,  287. 
J  Bull.  Mus.  Comp.  Zool.,  1880,  vii.  177,  118. 
3 


18  THE  ORIGIN   AND   ALTERATION   OF   ROCKS. 

interior  have  been  liquid  since  the  Azoic  time,  it  may  be  replied  that  if 
contraction  suffices  to  keep  up  the  heat  of  the  sun  to  an  approximate 
uniformity,  so  too  the  contraction  of  the  earth  would  tend  to  maintain  a 
uniform  temperature  in  the  earth's  interior ;  a  point  that  it  is  necessary  to 
consider  in  all  discussions  relating  to  the  earth's  age.  It  may  again  be 
suggested  that,  while  basic  rocks  of  the  same  character  as  those  seen  to- 
day were  erupted  in  the  early  ages  of  the  earth,  yet  there  has  been  on  the 
whole  a  progression  from  the  acidic  to  the  basic,  in  relative  abundance,  from 
earlier  to  later  times.  Furthermore,  owing  to  the  irregularity  in  thickness 
with  which  the  earth's  crust  has  apparently  solidified,  great  diversities  would 
be  expected  to  exist  in  that  part  immediately  below  the  crust  in  different 
portions  of  the  earth.* 

Whether  volcanic  and  all  other  eruptive  rocks  came  from  material  that 
has  never  cooled  to  a  solid  state  since  the  earth  began  to  solidify,  or  whether 
they  are  derived  from  a  portion  that  solidified,  but  has  since  been  reliquefied, 
is  a  problem  for  the  future,  the  solution  of  which  hinges  on  the  origin  of 
the  partially  destroyed  materials  in  the  rocks  themselves,  —  were  they 
caught  up  on  the  passage  of  the  lava  to  the  earth's  surface,  or  are  they 
the  remains  of  a  prior  crystallization  ? 

If  we  turn  to  Sorby's  method  for  determining  the  origin  of  rocks  by  the 
inclusions  in  the  contained  minerals,  we  find  that  it  may  possibly  answer 
in  recent,  surface-formed  rocks;  but  that  in  the  old  and  altered  forms  it 
seems  to  carry  us  astray,  and  serves  but  to  retard  the  advance  of  our  knowl- 
edge of  rock  formation.  This  is  especially  the  case  if  the  secondary  min- 
erals, like  quartz,  have  been  formed  later  in  the  rock  in  question  by  the 
action  of  hot  waters.  Conclusions  regarding  the  origin  of  a  secondary  or 
foreign  mineral  included  in  a  rock  ought  not  to  be  transferred  to  the  rock 
itself,  as  those  who  use  Sorby's  method  are  in  a  habit  of  doing. 

The  somewhat  common  argument  that  a  rock  associated  with  crystalline 
schists  must  have  the  same  origin  as  the  schists,  would  make  a  dike  in  slate 
of  the  same  origin  as  the  slate.  Association  of  rocks  proves  nothing,  for  in 
volcanic  districts,  in  limited  areas  even,  rocks  of  every  character  can  be 
found  together.  Should  we  then  hold  that  because  some  were  sedimentary, 
all  the  others  were  so  ?  Or,  again,  should  we  claim  that  because  some  were 
eruptive,  all  the  rest  were  eruptive  ?  No  !  we  ought  to  prove  the  origin  of 
each  rock,  and  in  every  locality  in  which  it  occurs,  so  far  as  possible,  and 
when  evidence  is  wanting  leave  the  question  as  undetermined. 

*  Whitney's  Volcanoes,  Earthquakes,  aud  Mountain  Building,  pp.  69-107. 


IMIKIMTIONS  OF  TERMS  USED.  19 

A  region  in  which  eruptive  rocks  abound  is  a  region  in  which  crystal- 
line schists  would  naturally  he  expected  to  occur;  for  here  the  conditions  of 
mi'tamorphism  are  best  developed,  —  conditions  that  affect  and  metamor- 
phose all  the  associated  rocks,  both  eruptive  and  sedimentary,  according  to 
their  composition  and  physical  structure.  Eruptive  rocks,  whether  in  dikes 
or  lava  Hows,  ashes  or  detritus  of  any  kind,  frequently  possess  the  charac- 
ters of  crystalline  schists;  must  they  therefore  be  regarded  as  being  of 
sedimentary  origin  ?  The  writer  has  seen  dikes  of  crystalline  schists  cut- 
ting directly  across  schistose  conglomerates  and  other  sedimentary  rocks. 
AY;is  he  to  conclude  that  these  dikes  of  schist  were  sedimentary,  and  had 
been  intruded  in  the  form  of  schists;  or  rather  that  they  were  of  eruptive 
origin,  —  the  original  rock  having  been  later  metamorphosed  into  a  schis- 
to<e  rock?  He  has  also  seen  mica  schists  inclosed  in  distinctly  eruptive 
granites.  If  the  law  of  association  is  worth  anything,  then  should  it  not  be 
claimed  that  these  schists  were  eruptive  ?  Ought  not  the  evidence  and  the 
tacts  of  the  origin,  and  not  the  association,  to  be  taken  as  proof  of  what  that 
origin  was  ? 

At  this  time,  when  the  tendency  is  so  strong  to  consider  almost  every- 
thing the  result  of  stratification,  it  seems  necessary  here  to  call  attention  to 
some  characters  that  for  the  most  part  are  common  to  all  rocks,  whatever 
may  be  their  origin.  While  these  characters  are  taken  as  proof  positive  of 
sedimentation,  in  reality  they  have  no  bearing  upon  the  question  unless 
they  are  exclusively  confined  to  one  class. 

Lamination  in  a  rock  is  one  of  these  characters;  which  may  be  defined  as 
a  structure,  either  original  or  superinduced  in  rocks  of  various  kinds,  causing 
them  to  tend  to  splii  into  more  or  less  parallel  layers. 

This  structure  is  very  common  in  many  eruptive  rocks,  especially  those 
of  a  fine-grained  or  glassy  character,  and  which  have  become  metamor- 
phosed. In  many  rocks  an  appearance  of  lamination  is  brought  about  by 
the  deposition  of  coloring  matters  in  bands,  and  this  pseudo-lamination  even 
has  been  oftentimes  taken  for  stratification. 

Joint  planes  may  be  defined  as  fissures  traversing  rocks  in  a  regular  or 
irregular  manner,  independently  of  any  other  structural  planes,  induced 
during  the  time  of  the  consolidation  of  the  rock  or  later,  and  dividing  it 
into  masses  of  greater  or  less  size.* 

These    planes    are    frequently    mistaken    for    bedding    planes,    both    in 

*  Faults  and  fissure  veins  are  but  modified  joints. 


20  THE   ORIGIN  AND   ALTERATION   OF   EOCKS. 

sedimentary  and  eruptive  masses,  particularly  in  regions  of  crystalline  rocks. 
Eruptive  rocks  subjected  to  pressure  in  dikes,  or  when  they  are  metamor- 
phosed, tend  to  take  upon  themselves  a  more  or  less  parallel  jointing,  which 
superficially  resembles  stratification,  and  which  to  the  writer's  personal 
knowledge  has  been  taken  for  bedding  planes  by  some  of  the  most  promi- 
nent geologists  in  the  United  States. 

Cleavage  is  another  structure,  which  by  many  is  supposed  to  be  confined 
to  sedimentary  rocks ;  but  this  is  evidently  not  the  case.  This  may  be 
defined  as  a  tendency  in  rocks  to  split  more  or  less  indefinitely  into  thin 
plates,  independently  of  any  original  structure  in  the  rock  masses.  In  the 
same  series,  the  finer  the  grain  the  more  perfect  is  the  cleavage ;  therefore 
it  is  best  developed  in  argillites,  fine  grained  eruptive  rocks,  and  volcanic 
ashes.  The  presence  of  cleavage  characters  in  the  last  two  series  of  rocks 
ought  to  make  us  careful  in  deciding  upon  the  origin  of  any  rocks  from 
considerations  connected  with  their  cleavage  alone  :  further  evidence  should 
be  obtained,  of  a  more  decisive  character. 

Foliation  is  another  rock  structure  belonging  to  rocks  of  diverse  origin, 
and  due  either  to  the  existence  of  bands  or  layers  of  different  minerals,  or 
to  a  more  or  less  parallel  arrangement  of  foliated  minerals,  like  talc,  mica, 
chlorite,  etc.  This  structure  may  even  be  taken  by  rocks  which  are  not 
composed  of  foliated  minerals,  as,  for  instance,  limestone.  Foliated  speci- 
mens of  limestone  destitute  of  mica  have  been  brought  to  the  writer  from 
Western  Massachusetts,  as  being  mica  schist,  and  considered  as  supporting 
the  view  that  in  that  region  the  limestone  passes  directly  into  mica  schist. 

It  is  very  difficult  to  give  any  definition  of  foliation  that  will  cover  all 
cases  of  this  structure,  but  it  may  in  general  be  said  to  signify  a  structure 
induced  (not  congenital)  in  rock  masses  by  the  arrangement  of  certain  crys- 
tallized minerals,  or  of  a  single  mineral,  in  more  or  less-parallel  lines,  along 
which  the  crystals  lie,  flatways  or  lengthways.  It  has  been  found  that  in 
sedimentary  rocks  the  foliation  may  or  may  not  correspond  with  the  stratifi- 
cation planes,  and  until  in  each  case  it  is  proved  to  do  so  it  cannot  be  taken 
as  marking  the  original  planes  of  deposition.  The  causes  that  produce 
cleavage  in  some  rocks  seem  to  induce  foliation  in  others.  An  example 
of  this  is  to  be  observed  at  the  point  of  land  south  of  Boston  Harbor,  known 
as  Squantum.  At  this  locality  the  stratification  and  cleavage  of  the  argil- 
lite  and  sandstone  are  seen  to  differ  considerably  from  one  another,  while 
the  conglomerate  lying  between  has  its  pebbles  somewhat  rearranged, 


FOLIATION  —  FLUIDAL  STRUCTURE.  21 

giving  rise  to  a  schistose  or  semi-foliated  structure.  These  foliation  planes 
correspond  with  the  cleavage  planes,  but  not  with  the  original  bedding  of 
the  rock. 

Foliation  is  of  frequent  occurrence  in  metamorphosed  eruptive  rocks, 
giving  rise  to  schistose  forms  which  are  ordinarily  taken  for  micaceous, 
chloride,  and  other  schists,  which  are  usually  regarded  as  sedimentary. 
All  these  are  cases  of  similar  structures  and  similar  rocks,  resulting  from 
the  alteration  of  rocks  of  diverse  origin,  but  of  similar  chemical  com- 
position. Foliation  usually  corresponds  to  the  lines  of  pressure,  —  either 
from  the  walls  or  from  the  surface  downward,  and  is  usually  brought  about 
by  recrystallization  of  the  rock  constituents  during  the  process  of  altera- 
tion. Since  rocks  of  every  kind  are  subject  to  metamorphism,  and  none 
more  so  than  the  basic  eruptive  ones,  it  is  natural  to  suppose  that  highly 
altered  eruptive  as  well  as  sedimentary  rocks  would  display  that  character 
of  structure  which  is  designated  by  the  term  foliation. 

.Many  rocks  which  can  hardly  be  said  to  possess  lamination  or  foliation, 
show  nevertheless  a  schistose  or  fissile  structure,  which  is  a  property  of  all 
more  or  less  altered  rocks,  —  a  superinduced  structure,  and  not  a  congenital 
one.  Hence,  this  structure  cannot  be  taken  as  being  confined  to  a  single 
class  of  rocks,  and  therefore  a  diagnostic  for  that  class,  as  has  been  done  by 
some  geologists. 

Fluidal  structure  is  a  character  induced  in  eruptive  rocks  through  their 
having  moved  or  flowed  when  in  a  liquid  or  pasty  condition.  It  is  best  seen 
in  the  glassy  and  acidic  eruptive  rocks  and  furnace  slags.  This  structure 
belongs  to,  and  is  characteristic  of  eruptive  rocks.  It  is  by  no  means  con- 
fined to  lava  flows,  but  is  also  to  be  seen  in  dikes.  The  difficulty  in  regard 
to  employing  it  as  a  diagnostic  character  arises  from  the  close  resemblance 
of  it  to  other  structures  in  altered  rocks,  and  its  obliteration  by  secondary 
alteration  in  the  rock  mass.  A  schistose  structure  induced  in  rocks  by  alter- 
ation is  the  one  structure  that  under  the  microscope  is  most  often  mistaken 
for  fluidal  structure.  Fluidal  structure  has  been  taken  for  bands  of  sedi- 
mentation in  a  large  number  of  instances,  particularly  in  the  older  acidic 
rocks  like  felsitc  and  granite. 

The  bands  of  chemical  deposition,  as  in  the  case  of  silica  from  hot  springs, 
have  in  some  instances  been  confounded  with  the  fluidal  structure  of  erup- 
tive rocks,  although  distinct  from  that  both  in  character  and  cause. 

In  the  employment  of  the  fluidal  characters  in   the  older  rocks,  great 


22  THE   ORIGIN  AND   ALTERATION   OF   ROCKS. 

care  needs  to  be  taken  to  prevent  their  being  confounded  with  the  super- 
induced structures  in  the  same  rocks,  for  such  mistakes  are  of  very 
frequent  occurrence. 

Arguments  from  analogy  should  only  be  permitted  in  deciding  the  ques- 
tion of  the  origin  of  any  rock  Avhen  no  other  evidence  exists ;  and  then  such 
arguments  should  be  admitted  to  be  of  a  doubtful  character,  and  not  held  to 
be  proof  positive.  Another  prominent  fallacy  in  petrography  is  the  argument 
that  as  the  conditions  are  in  one  region,  so  must  they  be  in  another,  —  while 
no  effort  is  made  to  find  out  what  the  real  conditions  are  in  the  latter. 

The  origin  of  the  older  rocks,  comprising  the  districts  regarded  as  Azoic 
or  Archaean,  and  the  principles  on  which  they  have  to  be  subdivided  into 
groups,  or  ages,  have  an  important  bearing  upon  the  classification  of  rocks. 
The  prevalent  views  regarding  the  constitution  of  these  older  formations 
were  looked  upon,  by  the  writer,  as  opposed  to  petrographical  facts ;  hence 
it  became  necessary  to  make  a  careful  examination  of  the  published  evi- 
dence in  behalf  of  these  views.  This  has  been  done  and  duly  published,* 
with  the  result  that  no  real  evidence  has  been  found  sustaining  the  current 
views ;  and  thus  the  petrographer  is  free  to  follow  the  data  of  his  science. 

The  structure  of  the  districts  of  crystalline  rocks  can  in  most  cases  be 
explained  in  the  following  way.  Let  the  reader  imagine  a  region  covered 
by  rock,  either  eruptive  or  sedimentary.  Then  suppose  that  here  eruptive 
(volcanic)  action  begins,  and  ashes,  mud,  lava,  and  the  other  accompaniments 
of  such  action  are  mingled  together.  The  earlier  sedimentary  rocks,  and  the 
volcanic  material  are  later  cut  through  and  through  by  dikes  —  faulted  and 
jointed,  contorted,  and  if  on  a  sea-shore,  subjected  to  wave  action  before  the 
latter  are  fairly  cold. 

We  might  thus  have  mingled  in  inextricable  confusion  lava  flows,  indur- 
ated and  contorted  sedimentary  rocks,  ashes,  scoria,  mud-flows,  dikes,  marine 
deposits,  in  short,  every  known  form  of  rock  which  can  be  produced  by  the 
combined  action  of  volcanic,  pluvial,  and  marine  agencies.  After  this,  then 
imagine  the  decline  of  the  eruptive  power,  with  the  accompanying  gaseous 
and  thermal  water  action.  Imagine  the  changes  in  the  rock  structure  that 
these  agents  would  produce,  as  previously  mentioned  under  rock  alteration, 
including  vein  phenomena;  and  then  consider  what  would  be  the  effect  upon 
such  a  district  of  the  action  of  every  conceivable  geological  agency  during 
the  countless  years  since  the  early  geological  ages.  Then  suppose  that  some 

»  Bull.  Mua.  Comp.  Zool.,  1880,  vii.  No.  1;  1884,  No.  11. 


EKITTIYK  AND  SKI  >IM  KNTAKY   A(  IKXCI  KS  DISCUSSED.  23 

geologist  be  placed  upon  this  old  volcanic  ground  worn  down  to  its  roots, 
its  locks  altered  or  metamorphosed,  its  remnants  of  mingled  lava  flows,  eject- 
amenta,  and  marine  deposits,  and  let  him  be  asked  to  give  its  history.  If  he 
Avere  educated  in  the  prevailing  views  current  in  American  geological  liter- 
ature, it  is  probable  that  he  would  declare  that  this  was  an  old  chemical 
or  sedimentary  deposit,  which  had  been  buried  thousands  on  thousands  of 
fort  deep  under  other  sedimentary  deposits,  and  in  which,  owing  to  the 
inclosed  moisture  and  the  rise  of  the  internal  heat,  an  aqueo-igneous  solu- 
tion had  set  in,  rendering  the  formation  plastic.  He  would  also  say,  that 
owing  to  the  generated  gases  and  pressure,  the  lower  portions  of  the  deposit 
had  been  forced  into  the  upper  ones,  and  every  gradation  had  been  produced 
between  the  normal  sedimentary  rock  .and  eruptive  forms,  which  pass  by 
insensible  gradations  into  each  other.  How  easy  and  simple  would  this 
explanation  be!  —  nothing  could  be  shown  which  the  authors  of  such  theories 
could  not  explain.  But  how  false  in  onr  supposed  case  such  an  explanation 
would  be.  If  we  add  to  onr  supposed  volcanoes  massive  eruptions,  with  or 
without  fragmental  ejections  (explosive  action),  shall  we  not  have  the  same 
petrographical  features  that  now  exist  in  regions  of  the  older  crystalline 
rocks  ?  —  and  is  the  explanation  generally  adopted  for  them  any  more 
accurate  ? 

The  intermingling  of  eruptive  and  detrital  deposits  here  supposed  is 
described  in  almost  every  work  on  volcanic  action,  and  it  has  been  clearly 
shown,  in  many  of  these  districts  of  older  crystalline  rocks,  that  the  series 
of  events  here  indicated  has  been  very  common. 

That  sedimentation  has  done  its  part  the  writer  believes,  and  he  has  not 
the  slightest  wish  to  belittle  its  importance;  but  that  it  has  done  everything 
he  does  not  believe.  Whether  any  of  the  first-cooled  masses  may  ever  be 
found,  is  a  problem  for  the  future ;  but  that  we  have  to  do  with  material 
that  was  fluid  before  sedimentation  began,  we  consider  is  clearly  established. 

To  volcanic  phenomena,  whether  explosive  or  massive,  and  to  the  as- 
sociated water  action,  appear  to  be  due  the  phenomena  of  crystalline  rocks, 
which  occur  in  any  and  every  age  from  the  earliest  times  to  the  present. 

Especial  stress  has  here  been  placed  upon  the  characters  and  phenomena 
of  eruptive  rocks,  in  hopes  of  bringing  about  a  state  of  geology  in  which 
the  opposing  eruptive  and  sedimentary  agencies  shall  both  have  their  proper 
share,  —  which  at  present  they  do  not  have,  on  account  of  the  extreme  to 
which  the  advocates  of  sedimentation  have  now  carried  their  views. 


24  THE  OEIGIN  AND  ALTERATION  OF  ROCKS. 

The  views  of  sedimentation  have  been  pushed  so  far  that  one  wonders  if 
Strabo,  after  he  had  described  the  volcanic  characters  of  Vesuvius,  was  not 
told  by  his  cotemporaries  that  it  was  all  a  mistake  —  that  the  peculiar  char- 
acter of  the  rocks  was  owing  to  chemical  deposition  or  to  mechanical  sedi- 
ments ;  that  all  showed  the  slow  accumulations  of  millions  of  years  on  a  slowly 
subsiding  sea-floor ;  that  the  whole  had  been  buried  many  miles  under  the 
accumulating  sediments,  rendered  plastic,  causing  dikes  to  be  formed ;  that 
all  the  different  rocks  passed  by  insensible  gradations  into  one  another,  etc. ; 
and  that,  finally,  the  whole  mountain  was  carved  out  by  the  slow  process., 
of  the  removal  of  the  sediments,  and  was  imdoubtedly,  owing  to  the  crys- 
talline character  of  its  rocks,  one  of  the  earliest  formations  of  the  globe. 

In  working  in  regions  of  crystalline  rocks,  the  principles  should  be  used 
that  one  would  employ  in  studying  districts  in  which  modern  volcanic  action 
has  existed,  as  about  Naples,  Mount  Etna,  Iceland,  western  North  and  South 
America,  and  Japan. 

If  this  is  done,  and  the  older  districts  are  examined  by  the  aid  of  the  light 
given  by  the  modern  eruptive  formations,  the  writer  believes  that  the  pres- 
ent obscurity  enveloping  the  former  would  be  cleared  away.  The  greatest 
difficulties  in  the  study  of  such  regions  seem  to  have  been  in  the  theoretical 
views  of  the  observers  themselves.  The  question  regarding  such  rocks 
should  be,  what  are  the  facts,  and  not  what  are  the  theories. 

It  seems  to  the  writer  clear  that  the  earlier  formations  of  which  we  have 
any  record  in  the  earth's  crust  were  not  derived  from  the  waste  of  earlier 
lands,  but  rather  that  they  are  for  the  most  part  eruptive,  if  not  portions  of 
the  first  formed  crust ;  and  that  the  fragmental  portions  were  eruptive  ashes, 
or  were  derived  from  the  waste  of  eruptive  material.* 

The  burden  of  proof  rests  upon  the  advocate  of  ancient  destroyed  conti- 
nents, to  show  that  the  materials  which  he  supposes  came  from  such  lands 
could  not  have  been  derived  from  the  eruptive  action  of  that  early  day. 

The  term  eruptive,  or  volcanic,  has  been  applied  in  this  paper  to  all  rocks 
coming  from  beneath  the  surface,  showing  signs  that  they  have  been  in  a 
fluid  condition,  —  whether  ancient  or  modern,  —  for  nature  has  not,  to  my 
belief,  drawn  any  line  in  her  rocks  between  the  younger  volcanic  and  the 
older  plutonic  forms,  but  all  form  a  continuous  and  harmonious  whole. 

*  Gcikie,  Text  Book  of  Geology,  pp.  12,  13. 


THE   MI  NEK  A  I.   CONSTITUENTS   OF  ROCKS.  25 


SECTION  III.  —  The  Origin  ami  ]!<•  hit  inns  of  the  Mineral  Constituents  of  Rocks. 

TAKING  the  consolidation  of  any  rock  as  the  initial  point,  particularly 
those  of  an  eruptive  nature,  the  constituents  fall  into  one  of  three  classes: 
I.  Those  of  prior  origin ;  II.  Those  formed  at  that  time  ;  III.  Those  of  later 


origin.* 


The  minerals  of  the  first  class  naturally  fall  into  two  divisions,  in  the 
eruptive  rocks. 

1.  Those  that  are  characteristic  of  the  rock  species. 

2.  Those  that  are  accidental,  being  probably  caught  up  in  the  passage 
upward  or  during  the  outflow.     Similar  divisions  are  found  to  a  greater  or 
less  extent  in  the  sedimentary  rocks,  according  as  they  were  derived  from 
one  or  more  rocks,  and  also  according  to  the  preponderance  of  different 
rock  fragments  and  minerals  in  them. 

The  minerals,  and  fragments  of  minerals  and  rocks,  occurring  in  rock 
masses  that  belong  to  the  first-class,  have  an  important  be(aring  upon  the 
questions  of  the  origin  and  relations  of  rocks  —  so  much  so  that  more  atten- 
tion will  be  given  to  them  in  the  future  than  has  been  the  case  in  the  past. 
These  are  in  a  great  measure  characteristic  of  the  rock  species,  and  should 
have  a  very  great  weight  in  the  nomenclature  of  sedimentary  rocks ;  for  one 
of  the  most  important  questions  regarding  these  is,  what  was  the  original 
material  from  which  they  were  derived?  In  the  volcanic  rocks  these  minerals 
are  distinguished  generally  by  the  effect  that  the  magma  has  produced  upon 
them  —  the  blackening,  breaking,  tearing,  and  dissolving  action  which  is  so 
conspicuous  in  the  case  of  olivine  and  hornblende;  while  in  quartz  it  is  shown 
in  the  fractures,  the  rounding  of  the  grains,  and  the  interpenetration  of  the 
magma.  Frequently  these  foreign  materials,  especially  quartz,  have  radiating 
rings  of  the  groundmass  surrounding  them,  these  rings  being  largely  composed 
of  crystals  standing  perpendicular  to  the  surface  of  the  inclosed  piece.  In  all 
rocks  of  an  eruptive  nature,  the  fragments  are  apparently  either  inclusions 
caught  in  the  passage  upward,  or  during  the  surface  flow  of  the  lava,  or  else 
derived  from  the  remeltiug  of  the  more  crystalline  portions  of  these  or  other 
rocks  at  the  time  of,  or  prior  to  the  eruption ;  especially  when  the  eruption 

»  A.  Michel  Levy,  Bull.  Soo.  fieol.  France,  1874   (3),  iii.  199-230;  Ann.  Mines,  1875   (7),  viii.  341- 
340;  \Vadsworth,  Bull.  Mu.,.  ('.m,p.  Zoul.,  1S79,  v.  277,  278. 


26  THE  MINERAL  CONSTITUENTS   OF   ROCKS. 

took  place  in  an  old  vent,  from  which  the  plug  of  lava  and  ashes  must  be 
removed  before  the  outflow  could  occur. 

The  action  of  lavas  upon  these  foreign  inclusions  seems  to  be  that  of  a 
corrosive  dissolving  hot  magma  or  solution,  which  penetrates  and  gnaws  its 
way  into  the  included  fragments.  Two  cLisses  of  foreign  materials  seem  to 
be  characteristic  of  most  of  the  eruptive  rock  species  —  simple  minerals,  and 
rock  fragments.  The  latter  are  either  the  same  as  the  inclosing  rock  or  else 
they  are  the  same  as  some  rock  known  to  have  reached  the  earth's  surface 
earlier  in  order  of  time.  These  mineral  inclusions  characterize  the  same 
rock  type"  from  the  earliest  times  to  the  present,  when-  and  where-ever  they 
may  occur.  All  this  indicates  some  deep  seated  universal  cause  beyond  the 
influence  of  sedimentary  rocks. 

These  characteristic  minerals,  too,  are  not  such  as  occur  in  sedimentary 
rocks ;  while  no  such  admixture  of  material  exists  in  the  eruptive  forms  as 
would  naturally  be  expected  to  occur  if  they  were  .formed  from  sediments. 
Then  too,  the  minerals  and  fragments  of  the  more  difficultly  altered  sedi- 
mentary rocks  ought  to  have  remained  side  by  side  with  these  easily  alter- 
able foreign  minerals  in  eruptive  rocks,  if  the  latter  rocks  are  the  re-fused 
portions  of  the  former.  The  microscopic  characters  of  the  eruptive  rocks 
are  to  my  mind  utterly  opposed  to  any  theory  that  they  come  from  sedi- 
ments, or  anything  else  than  the  original  liquid  material  of  the  earth. 

The  second  class  of  rock  constituents  naturally  occupies  the  most  promi- 
nent place  in  recent  volcanic  rocks,  and  a  more  subordinate  one  in  the  older 
eruptive  and  sedimentary  ones.  In  eruptive  rocks,  the  indigenous  materials 
are  the  products  of  the  magma  when  unacted  upon  by  extraneous  agencies. 
It  is  doubtful  if  any  minerals  come  under  this  head  —  direct  primary  pro- 
ducts of  crystallization  of  the  magma  —  except  anhydrous  silicates  and 
oxides,  a  few  phosphates,  sulphides,  and  native  elements,  the  other  minerals 
in  the  rocks  belonging  to  the  other  two  classes. 

The  third  class  becomes  very  prominent  in  the  older  and  altered  rocks, 
and  includes  the  hydrous  and  some  anhydrous  oxides  and  silicates,  carbon- 
ates, and  most  sulphides. 

These  forms  are  the  products  both  of  alteration  taking  place  in  the  rock 
mass  and  of  material  brought  into  the  rock  from  extraneous  sources.  In 
one  case  the  chemical  constitution  of  the  rock  remains  essentially  unim- 
paired, while  in  the"  other  that  constitution  is  changed  to  a  greater  or  less 
degree.  The  causes  of  these  alterations  in  ancient  and  modern  volcanic 


THEIR  ORIGIN'   AND   RELATIONS.  27 

rocks  is  but  imperfectly  known,  but  the  changes  probably  take  place  under 
the  influence  of  percolating  waters.  That  these  changes  are  slow  in  many 
cases  is  rendered  prohaMo  by  the  fact,  that  when  rocks  have  been  exposed 
to  rapid  alterations  by  hot  and  mineral  waters,  the  result  is  a  general  de- 
struction of  the  rock  mass,  a  disintegration  of  it  as  a  whole,  and  not  such 
changes  as  are  seen  in  rock  masses  in  general.  It  is  probable  that  both  cold 
and  thermal  waters  have  contributed  to  the  change,  as  the  latter  are  abun- 
dant in  volcanic  regions  at  the  present,  and  we  have  the  right  to  infer  that 
they  were  so  in  past  time  at  the  localities  in  which,  ancient  igneous  activity 
was  manifested. 

These  alterations  are  considered  to  be  molecular,  or  belonging  to  the 
rock  mass  as  a  whole,  although  some  portions  and  some  minerals  are  altered 
more  rapidly  than  others.  The  general  tendency  of  rock  alteration  seems  to 
be  the  breaking  up  of  the  original  constituents,  and  the  formation  of  quartz 
and  other  minerals,  that  give  to  the  rock  characters  closely  simulating  those 
of  sedimentary  rocks. 

The  sediments  also  undergo  the  same  changes,  and  in  extreme  cases 
produce  crystalline  schists  and  gneisses.  The  changes  in  them  are  appar- 
ently brought  about  by  the  same  agencies  as  the  changes  in  eruptive  rocks, 
and  thermal  waters  may  have  been  an  important  factor  in  producing  crys- 
talline structure  in  the  former. 

In  the  various  alterations  of  the  rocks  of  every  kind  the  new  mineral 
structures  come  apparently  from  the  segregation  of  mineral  matter,  either 
from  the  rock  or  adjacent  sources,  in  some  place  suitable  for  its  deposition. 
The  place  may  be  some  fissure  or  cavity,  or  it  may  be  in  the  solid  rock  mass 
itself,  by  the  removal  of  one  or  more  chemical  constituents  from  the  immediate 
point  of  action,  and  the  substitution  of  others.  So  far  as  the  rock  mass  goes 
when  no  foreign  material  is  carried  into  it,  these  changes  may  be  defined  as 
the  migration  or  aggregation  of  the  chemical  elements,  produced  by  their 
tendency  to  seek  such  unions  as  shall  expose  them  under  their  present  con- 
ditions to  less  disturbing  elements  than  their  former  relations  did  —  a  ten- 
dency to  pass  from  an  unstable  towards  a  more  stable  condition.  The  final 
result  of  these  changes  is,  usually,  to  produce  clays,  ochres,  quartz,  and  car- 
bonates ;  the  latter  of  which  while  not  stable  in  position,  are  apt  to  be  so  iu 
composition ;  e.  //.,  calcite,  while  readily  soluble  and  removed,  generally 
reappears  as  calcite  —  the  position  unstable,  the  union  stable.  The  general 
principle  of  change  is  the  same,  whether  the  mineral  matter  be  reprecipitated 


28  THE   MINERAL   CONSTITUENTS   OF   BOCKS. 

in  the  rock  mass  itself,  or  is  carried  out  and  deposited  in  any  contiguous 
cavity  or  fissure,  or  borne  away  to  be  deposited  from  thermal  or  mineral 
springs,  or  from  bog,  river,  lake,  or  ocean  waters. 

The  efforts  to  explain  the  changes  in  rocks  and  in  their  mineral  con- 
stituents by  theories  of  pseudomorphism  have  generally  failed,  because  the 
changes  have  been  attributed  to  the  single  minerals,  and  not  to  the  rock 
mass  as  a  whole. 

The  concentration  of  ores  in  rocks,  and  the  formation  of  mineral  veins 
seem  to  be  brought  about  by  the  same  process  as  the  more  common  altera- 
tion of  the  rock  mass,  or  the  storing  up  of  the  material  in  minute  fissures 
in  the  rock.*  The  only  difference  is  that  the  kind  of  material  and  its 
amount,  owing  to  the  size  of  the  receptacle  and  the  extent  of  the  action, 
is  such  as  to  make  it  commercially  valuable.  In  this  statement  there  would 
be  excepted  all  ores  that  can  be  proved,  as  some  iron  ores  have  been,  to  be 
of  eruptive  origin,  as  well  as  all  mechanical  deposits.  In  this  connection  it 
may  be  explicitly  stated,  the  writer  holds  the  view  that  the  elements  of 
most  of  the  ores  were  disseminated  through  the  original  and  eruptive  rocks, 
and  that  when  these  rocks  became  exposed  to  the  action  of  meteoric 
agencies,  these  scattered  materials  were  collected  and  deposited  in  the  veins 
and  segregations  in  which  they  are  now  formed.!  So  far  as  now  known, 
the  only  ore  of  eruptive  origin,  in  masses  sufficient  for  exploitation,  is  that 
of  iron,  which  is  so  only  in  part  of  its  occurrences.  If  this  view  is  cor- 
rect, it  would  follow  that  our  veins  and  most  of  our  ore  deposits  are  superfi- 
cial phenomena  J  of  the  earth,  and  that  mineralogy  and  economic  geology 
as  ordinarily  studied  relate  chiefly  to  the  secondary  products  of  mineral 
matter;  or,  they  are  the  sciences  of  abnormal  minerals. 

The  above  described  alterations  in  rocks  and  minerals,  and  the  localiza- 
tion of  mineral  deposits,  with  the  consequent  essential  original  unity  of 
ancient  and  modern  rocks,  naturally  follow  from  the  general  law  of  the 
passage  from  the  unstable  towards  a  more  stable  condition.  This  results 
from  the  fact  that  the  original  materials  of  the  earth,  whether  forming  the 
original  crust,  or  appearing  on  the  surface  as  eruptive  rocks,  are  in  a  higher 
state  of  energy  than  is  adaptable  to  the  surface  conditions  of  this  globe. 
They  are  unstable  both  in  temperature  and  in  the  majority  of  chemical 
combinations  formed  on  solidification,  and  heat  is  lost  with  a  resulting 

*  Bull.  Mus.  Comp.  Zool.,  18SO,  vii.  123-130;  Proe.  Bost.  Soc.  Nat.  Hist.,  18SO,  xxi.  01-103. 
f  Eng.  Min.  Jour.,  New  York,  1884,  xxvii.  361,  365. 
J  Whitney,  Aurif.  Gravels,  pp.  350-301. 


THEIE   CLASSIFICATION.  29 

dissipation  of  energy ;  while  the  chemical  elements  or  the  molecular  combi- 
nations tend  to  seek  new  unions  better  adapted  to  the  present  circumstances 
of  the  rocks.  These  changes  progress,  going  on  from  one  form  to  another. 
It  is  not  uncommon  to  find  that  as  steps  in  the  progress,  the  original  miner- 
als and  glass  are  altered  to  other  more  or  less  well  defined  minerals,  having 
sometimes  perfect  crystalline  form;  while  these  in  their  turn  yield  to  the  act- 
ing forces,  and  new  mineral  combinations  are  entered  into,  and  so  on  down- 
ward in  the  course  of  the  alteration.  It  may  be  said  that  an  eruptive  rock, 
when  it  has  passed  from  the  interior  to  the  exterior  of  the  earth,  becomes 
a  chemical  laboratory,  in  which  solutions,  reactions,  and  precipitations  are 
continually  carried  on  —  experiment  after  experiment,  change  after  change, 
succeed  one  another,  according  to  the  materials,  reagents,  and  conditions. 
But  they  always  progress  in  one  direction  ;  the  combination  last  formed  is 
;il\v;iys  more  stable  in  the  then  conditions  than  the  preceding  combinations 
were ;  with  any  change  of  condition  there  would  of  course  come  change  in 
relative  stability. 

The  induration  or  hardening  of  rocks  would  thus  oftentimes  be  no  index 
of  exposure  to  heat,  for  if  the  mineral  formed  or  infiltrated  into  the  rock 
mass  is  one  which  stands  high  on  the  scale  of  hardness,  e.  g.  quartz,  then 
induration  follows  as  a  matter  of  course. 

From  the  principle  of  passage  or  unstableness  it  follows  that  the  glassy 
state  is  nearest  the  primitive  condition,  and  is  to  be  looked  upon  as  the 
starting  point  of  the  indigenous  and  secondary  minerals  in  rocks;  hence  it 
should  come  first  in  our  study  and  be  traced  in  its  process  of  crystallization 
and  alteration. 

The  three  classes  of  products  above  discussed  will  be  mentioned  hereafter 
as  products  of  the  first,  second,  and  third  class,  or  as,  1st,  foreign ;  2d,  indi- 
genous; and  3d,  alteration  or  secondary  products. 

The  two  first  classes  have  been  collectively  and  singly  called  by  the 
writer  original  in  contradistinction  to  the  secondary  products. 

Cases  of  envelopment  occur  in  minerals  of  the  second  class  frequently, 
but  they  can  be  distinguished  as  easily  under  the  microscope,  in  rocks  not 
too  far  altered,  from  the  foreign  or  secondary  minerals,  as  a  coarse  conglom- 
erate can  be  distinguished  from  a  granite  by  the  naked  eye,  or  as  a  piece  of 
wood  joined  to  another  by  a  mortise  and  tenon  can  be  distinguished  from 
the  natural  growth  of  a  limb. 

The  various  changes  that  rocks  undergo  in  their  alterations  are  determined 


30  THE  MINERAL  CONSTITUENTS  OF  ROCKS. 

under  the  microscope,  the  same  as  changes  are  determined  in  objects  in 
botany,  zoology,  and  astronomy.  It  is  not  necessary  that  one  should  see 
an  acorn  grow  to  an  oak,  an  apple-seed  grow  to  an  apple-tree,  a  lamb  to  a 
sheep,  a  nebula  to  a  star,  before  he  can  reason  upon  the  growth  of  plants, 
animals,  and  stars.*  It  is  sufficient  to  be  able  to  study  these  in  various 
stages  of  their  growth,  in  order  to  make  out  their  history  —  to  examine 
numerous  specimens  that  exhibit  all  the  various  phases  of  existence,  to  make 
out  the  general  life  histor}'  of  the  individual.  So  in  lithology  the  history 
of  the  rocks  and  minerals  can  be  made  out  as  distinctly  and  certainly  as 
the  life  history  of  the  individuals  in  the  other  subjects  before  mentioned. 

In  applying  the  principles  of  thermo-optics  to  the  mineral  constituents 
of  rocks,  in  order  to  determine  at  what  temperature  the  rock  was  formed, 
it  should  be  remembered  that  it  is  only  the  minerals  of  the  first  class  to 
which  they  apply.  These  alone  must  have  been  subjected  to  the  heat  of 
the  liquid  magma  and  present  permanent  marks  of  that  action.  Of  course, 
nothing  can  be  asserted  concerning  the  temperature  to  which  a  liquid  has 
been  exposed,  from  either  the  thermo-optical  or  pyrognostic  characters  of 
the  resulting  minerals  arising  from  its  cooling  under  various  conditions;!  in 
other  words,  the  characters  of  a  mineral  after  it  is  formed  have  little  or 
nothing  to  do  with  what  it  was  before  it  was  formed,  except  so  far  as  the 
relation  may  have  been  shown  to  exist,  by  experiment  and  by  observation 
of  the  same  conditions.  Investigations  upon  the  thermo-optical  properties 
of  minerals  belonging  to  the  first  class  would  probably  lead  to  interesting 
results,  if  care  were  taken  to  select  such  as  are  typical  of  the  lava. 

It  should  also  be  kept  in  mind  that  the  conditions  under  which  minerals 
are  formed  from  the  crystallization  of  a  cooling  magma  are  different  from 
those  under  which  minerals  are  formed  in  veins,  fissures,  and  cavities,  or  by 
alteration  of  the  rock  mass ;  and  that  minerals  truly  of  the  second  or  indige- 
nous class  occupy  a  very  subordinate  position  in  our  mineral  cabinets. 

*  Peirce,  Ideality  in  the  Physical  Sciences,  18S1,  p.  69. 

f  As  well  predicate  what  was  the  temperature  of  the  water  glass  and  hydrochloric  acid,  from  the  amount  of 
beat  it  takes  to  fuse  the  chalcedonic  silica  which  they  form  under  suitable  conditions,  as  to  attempt  to  prove 
the  heat  of  a  liquid  magma  from  the  fusion  point  of  some  mineral  crystallizing  out  of  its  cooling  solution. 
The  temperature  at  which  a  mineral  fuses  and  the  temperature  at  which  it  formed  have  no  connection  with 
one  another,  except  in  the  case  of  crystallization  from  dry  fusion  ;  if  they  do,  how  hot  corals  must  be ! 


VALUE   01''   CHEMICAL  ANALYSIS   IN    L1THOLOGY.  31 


SECTION  IV.  —  Chemical  Analysis  of  Hocks. 

AT  the  present  time  the  most  that  chemical  analysis  seems  to  be  able  to 
do  for  the  lithologist  is  to  give  the  composition  of  the  rock  as  a  whole. 
The  many  attempts  that  have  been  made  to  determine  the  mineralogical 
composition  of  rocks  by  unaided  chemical  analysis  appear  to  have  been  in 
almost  every  case  a  failure.  This  is  natural,  for  this  method  alone  is  unable 
to  take  into  account  the  three  different  classes  of  minerals  in  rocks,  and 
in  its  statements  has  to  proceed  as  if  all  the  minerals  were  the  pro- 
ducts of  free  crystallization  in  the  rock.  But  while  the  chemical  composi- 
tion remains  about  the  same,  every  gradation  in  structure  and  mineral 
composition  is  known  to  exist,  —  from  a  pure  glass  to  mixed  glass  and 
crystals,  to  a  purely  crystalline  rock,  and  to  one  in  which  all  the  mineral 
constituents  are  secondary  or  alteration  products.  Since  the  chemical 
composition  of  all  these  forms  is  essentially  the  same,  the  results  of  any 
calculation  of  the  percentage  and  kind  of  minerals  inclosed,  would  be 
nearly  the  same ;  but  how  different  from  the  reality  are  the  results  of  the 
calculation,  except  when  the  rock  is  composed  of  crystals  of  the  second 
class  alone.  Even  here  the  correctness  of  the  result  would  be  a  matter 
of  doubt. 

Chemical  analyses  of  rocks,  showing  their  ultimate  constitution,  if  made 
from  specimens  carefully  selected  and  studied  in  the  field,  and  further 
studied  microscopically,  would  aid  greatly  in  lithological  research.  Typical 
unaltered  specimens  are  needed  to  establish  rock  species  ;  and  for  such  work 
the  average  specimens  of  collectors  are  too  much  affected  by  surface  altera- 
tion, or  weathering,  to  be  used.  But  a  large  proportion  of  rock  analyses 
appear  to  have  been  made  from  such  unsuitable  specimens,  of  whose  struc- 
ture, mineral  composition,  and  field  relations  we  know  nothing,  or  next  to 
nothing;  this,  too,  when  the  chief  value  of  such  analyses  is  to  enable  us  not 
only  to  institute  comparisons  between  the  chemical  composition  of  the  rock 
analy/ed  and  that  of  other  rocks,  but  also  between  that  composition  and 
its  origin,  structure,  mineral  composition,  and  physical  relations. 

Chemical  analyses  could  be  made  of  great  service  in  lithology  by  taking 
a  graded  series  of  rocks,  beginning  with  the  unaltered  form,  and  passing 
gradually  into  the  extremely  altered  form,  comparing  step  by  step  the  chem- 
ical composition  with  the  changes  in  structure  and  mineral  composition. 


32  CHEMICAL  ANALYSIS   OF   EOCKS. 

There  is  a  vast  amount  of  unconscious  humbug  in  the  constant  attempts 
to  use  chemical  analyses  for  a  purpose  foreign  to  their  nature ;  that  is,  to 
determine,  as  before  mentioned,  the  mineral  composition  by  mathematical 
calculations  founded  on  rock  analyses.  All  these  efforts  appear  to  be  based 
on  an  entire  misconception  of  the  nature  of  rocks.  Nothing  better  illus- 
trates the  inutility  of  this  method  alone  for  the  purpose  of  determining  the 
mineral  composition,  than  a  comparison  of  the  speculations  of  chemists 
regarding  the  minerals  composing  the  stony  meteorites  and  the  actuality  as 
obtained  by  microscopic  examination. 

The  writer  holds,  as  the  result  of  his  studies,  that  the  chemical  analysis 
of  a  normal  rock  corresponds  with  its  species — that  is,  certain  percentages 
of  the  more  prominent  elements  can  be  laid  down,  beyond  the  extremes  of 
which  normal  rocks  belonging  to  that  species  will  rarely  if  ever  go,  and 
within  which  normal  rocks  of  other  species  will  rarely  if  ever  come.  This, 
of  course,  applies  especially  to  the  eruptive  rocks,  for  in  the  case  of  the 
sedimentary  ones,  every  degree  of  composition  is  to  be  expected  according 
to  the  sources  from  which  the  materials  composing  them  were  derived,  and 
the  amount  of  sorting,  chemical  replacement,  etc.,  they  have  undergone. 

The  more  highly  altered  or  weathered  eruptive  rocks,  especially  if 
chemical  constituents  have  been  removed,  and  either  replaced  or  not  by 
others,  would  not  be  normal  forms.  If  the  analyses  were  written  in  the 
percentages  of  the  elements,  instead  of  their  compounds,  it  is  thought  that 
the  chemical  relations'  between  the  different  rock  species  and  varieties 
would  be  more  clearly  apparent  than  at  present,  as  Nordenskiold  has 
shown  for  the  meteoric  peridotites.* 

From  the  manner  in  which  many  chemical  analyses  of  rocks  have  been 
made  (poor  work,  poor  specimens,  and  no  knowledge  of  the  rock)  the 
difficulties  in  the  way  of  proving  these  relations  are  great;  but  the  writer 
has  prepared  tables  which  show  them  in  an  approximate  manner. 

*  Nature,  1878,  xviii.  510,  511;  Geol.  FSren.  Forhandl.,  1S78,  iv.  45-61;  Zeit.  Deut.  geol.  Gesclls., 
1881,  xxxiii.  14-30. 


SCHEMES   OF   CLASSIFICATION —THEIR   RELATIVE   VALUE.  33 

SECTION  V.  —  Classification  based  on  Mineral  Composition. 

IF  the  artificial  schemes  of  lithological  classification  are  examined,  it 
will  be  found  that  they  are  generally  based  on  the  mineral  composition, 
the  geological  age,  and  the  structure  of  the  rocks,  some  rocks  even  being 
defined  by  a  statement  of  that  which  they  are  not,  or  that  which  they  do 
not  contain. 

It  does  not  accord  with  the  limits  of  this  paper  to  enter  upon  any  thor- 
ough critical  discussion  of  the  application  of  such  principles,  but  a  certain 
examination  of  them  may  be  made,  so  far  as  they  bear  on  the  method  of 
classification  it  is  proposed  here  to  use.  Amongst  the  minerals  of  which 
the  chief  use  is  made  in  classification  there  may  be  mentioned  the  feld- 
spars, including  leucite  and  nephelite,  also  olivine,  quartz,  the  micas,  pyrox- 
enes, and  the  amphiboles;  although  siny  mineral  is  liable  to  assume  in 
special  cases  sufficient  importance  in  these  artificial  schemes  to  found  specific 
distinctions  iipon. 

Of  these  minerals  the  most  important  are  the  feldspars,  and  on  their 
presence  or  absence,  and  on  the  species  or  type  of  feldspar  present  are 
founded  some  of  the  most  important  divisions  of  the  rocks.  In  order  to 
successfully  use  any  mineral  in  classification  it  is  necessary  that  it  should 
be  a  determinate  quantity  —  that  is,  it  should  always  have  in  the  rock  one 
mode  of  formation  only  —  that  its  specific  limits  shall  be  well  marked,  and 
that  it  shall  be  accurately  determinable  with  fair  facility. 

The  Feldspars. 

That  the  feldspars  originate  in  all  three  of  the  methods  given  previously 
for  the  origin  of  rock  minerals  —  foreign,  indigenous,  and  secondary  —  the 
writer  thinks  cannot  be  denied ;  although,  for  the  most  part,  they  appear 
to  be  indigenous.  In  classification  of  this  kind,  the  most  important  question 
about  the  feldspars  is,  what  are  their  divisions  and  the  diagnostic  characters 
of  them.  A  sketch  of  the  various  prominent  opinions  regarding  their 
constitution  will  best  answer  our  question. 

In  1846  Schoerer  held  that  the  feldspars  were  different  grades  of  satura- 
tion, of  a  radical    compounded  of  equal  atoms  of  R.  and  Al.*      Later  he 
remarked  t  that  it  was  permitted  to  regard  all  known  feldspars  as  chemical 

»  Ann.  Physik  Chcmie,  1846,  Ixviii.  337;  Am.  Jour.  Sci.  1848  (2),  vi.  61. 
f  Ann.  Physik  Cliemic,  Ixxxix.  19. 

5 


34  CLASSIFICATION   BASED   ON   MINERAL   COMPOSITION. 

combinations  of  either  (1)  anorthite  and  labradorite,  or  (2)  anorthite  and 
albite  (orthoclase),  or  (3)  labradorite  and  albite  (orthoclase). 

In  1850  Delesse  said :  "  I  have  already  had  occasion  to  remark  that  we 

0 

have  hitherto  attached  too  much  importance  to  the  varieties  of  the  feldspars 
of  the  sixth  crystalline  system,  and  that  nature  has  not  always  been  limited 
by  the  divisions  established  among  them  by  chemists  and  geologists ;  the 
same  rock  sometimes  containing  several  varieties  of  these  feldspars."  In 
the  last  reference  Delesse  had  also  pointed  out  that  the  composition  of  the 
feldspar  was  not  constant  even  in  the  same  rock  from  the  same  locality. 

In  1851  Hermann  taught  that  in  the  feldspars  were  two  molecules :  one 
denoted  by  a  =  (R  Si3  -j-  Sis), 

and  the  other  by  b  =  (R  Si   -f-  Si). 

Of  these  molecules  the  species  were  thus  compounded  (giving,  however, 
from  his  list  only  those  species  of  importance  to-day) :  — 


Orthoclase    = 

a 

Albite            = 

a' 

Anorthite      = 

b 

.     ,    . 

a  +  b 

Andesite       — 

2 

T,:iVn*nrlnritp   — 

1      O    L 

a  -j-  o  o 

Oligoclase     =5a+3b 

The  union  in  this  case  was  regarded  as  a  molecular  union,  and  not  a 
chemical  combination  between  the  atoms,  f 

Sartorius  von  Waltershausen,  in  his  work  "  Ueber  die  vulkanischen 
Gesteine  in  Sicilien  und  Island,  und  ihre  submarine  Umbildung,"  published 
in  1853,  advanced  the  theory  that  there  were  three  definite  triclinic 
feldspars,  i.  e.  anorthite,  albite,  and  krablite,  and  that  the  other  triclinic  feld- 
spars were  formed  by  varying  compounds  of  these.  Krablite,  or  baulite,  J 
was  then  supposed  to  be  a  definite  silicate,  with  the  atomic  ratio  1:3:  24, 
as  determined  by  the  researches  of  Forchhammer§  and  Genth ;  ||  but  it  has 
since  been  shown  to  be  a  mineral  aggregate  or  rock,  referred  at  first  to  the 

*  Bull.  Soc.  Ge"ol.  Prance,  1850  (2),  vii.  526  ;  sec  also  Ann.  Mines,  1847  (4),  xii.  266,  267  ;  1849,  xvi. 
327,  32S. 

f  Jour.  Prakt.  Chemie,  1851,  lii.  256-258. 

$  Landgrebo,  Minerulogie  der  Vulcane,  1870,  pp.  60,  227. 

§  Oversigt  over  det  Kgl.  danske  Videiiskaberues  Selskabs  Forhandliiiger,  etc.,  1842,  pp.  43-55  ;  Jour. 
Prakt.  Chemie,  1843,  xxx.  394. 

||  Ann.  Chemie  Pharm.,  1848,  Ixvi.  271. 


COMPOSITION"  OF  THE  FELDSPARS.  35 

quartz  trachytes,*  and  later  to  the  liparites  or  rhy elites,  f  which  now 
include  most  of  the  quartz  trachytes  of  the  older  authors.  Bunsen,  indeed, 
maintained  both  before  and  after  1853,  that  baulite  was  a  mechanical  mix- 
ture —  a  rock,  and  not  a  mineral,  t 

In  1854  Dr.  T.  Sterry  Hunt  stated  that  the  triclinic  feldspars  constituted 
a  genus,  of  which  albite  might  be  taken  as  one  representative,  and  anor- 
thite  as  the  other.  The  intermediate  feldspars  might  be  distinct  species,  or 
they  might  be  looked  upon  as  variable  mechanical  mixtures  of  the  two  typi- 
cal feldspars,  albite  and  anorthite.  A  similar  mixture  of  albite  with  a  potash 
feldspar,  and  anorthite  with  a  soda  or  magnesian  one,  as  well  as  of  orthoclase 
with  a  lime  or  potash  feldspar,  were  regarded  as  probable.  Hunt  distinctly 
objects  to  any  idea  that  these  variable  feldspars  were  formed  by  chemical 
unions  between  the  different  types,  and  makes  it  clear  that  he  had  in  rnind 
the  process  of  envelopment  and  variable, "  mechanical,  contemporaneous 
intercrystallization,  on  which  he  founded  his  doctrines  of  the  origin  of 
crystalline  rocks,  pseudomorphism,  and  metamorphism.  In  this  he  fol- 
lowed Scheerer's  views  regarding  the  relations  of  iolite  and  aspasiolite, 
and  of  olivine  and  serpentine.  The  proportions  of  these  intermixtures  of 
the  feldspars  were  regarded  by  Hunt  as  entirely  variable  and  indefinite, 
being  "  such  mixtures  of  species  as  constantly  take  place  in  the  crystalliza- 
tion of  homoeomorphous  salts  from  mixed  solutions,"  and  he  explained  the 
process  in  every  case  in  the  same  way  as  he  did  in  the  case  of  perthite. 
That  this  view  of  the  mixture  of  the  feldspars  is  the  same  as  his  explana- 
tion of  pseudomorphism  can  be  seen  from  his  statement  that  the  latter  has 
resulted  in  many  instances  from  the  association  and  crystallizing  together 
of  homologous  and  isomorphous  species.  § 

In  1864  Professor  Gustav  Tschermak  advanced  the  theory  that  (excepting 
bvalophane  and  danburite)  there  were  three  distinct  species  of  feldspar: 
Orthoclase,  or  potash  feldspar;  Albite,  or  soda  feldspar;  and  Anorthite,  or 
lime  feldspar.  He  held  that  soda  and  potash  were  not  isomorphous,  and 
therefore  all  orthoclase  crystals  containing  soda  were  mechanical  mixtures 

•  Zirkcl,  Sitz.  Wien.  AkacL,  1863,  ilvii.  (1)  pp.  243,  244;  Lehrbuch  der  Petrograpliie,  1806,  i.  25; 
ii.  151-166. 

f  Zirkel  Die  mikroskopische  Beschaffeuheit  der  Mineralieu  imd  Gesteiiic,  1873,  p.  341. 

J  Bunsen  Ann.  Pliysik  Ciiemie,  1851,  Ixxxiii.  199,  201;  Ann.  Chemie  Phann.  1854,  Ixxxix,  98;  Preyer 
imd  Zirkel,  Reise  nach  Island  im  Summer,  1860  ;  pp.  317-324. 

§  Proc.  Am.  Assoc.  Adv.  Sci.,  1854,  viii.  237-547;  1S71,  xx.  1-59;  Am.  Jour.  Sci.,  1853  (2),  xvi.  218; 
1864,  xviii.  270,  271  ;  1'liil.  Mag.,  1855  (4),  ix.  354-303;  Geological  Survey  of  Canada,  Report  of  I'mirn  M, 
1  vV'i.  |i|i.  3;:i-:',v; ;  1838,  p.  180 ;  Canada  in  the  London  International  Exhibition,  1862,  p.  05  ;  Geology 
of  Canada,  1803,  p.  IMI. 


36  CLASSIFICATION   BASED   ON   MINERAL   COMPOSITION. 

(interlarainations  or  intercrystallizations)  of  orthoclase  and  albite.  Albite 
and  anorthite  were  looked  upon  as  two  distinct  species  of  triclinic  feldspar, 
and  it  was  held  that  labradorite,  andesite,  and  oligoclase  were  formed  from 
isomorphous  mixtures  of  albite  arid  anorthite,  —  that  is,  through  the  mo- 
lecular union  of  albite  and  anorthite,  in  definite  mathematical  propor- 
tions. These  mixtures  Tschermak  distinctly  held  were  not  mechanical,  but 
molecular. 

The  finding  of  potash  in  the  triclinic  crystals  formed  from  the  molecular 
union  of  albite  and  anorthite  was  explained  by  Tschermak,  by  the  supposi- 
tion that  some  orthoclase  was  mechanically  interlaminated.  Oligoclase, 
labradorite,  and  andesite  were  united  under  the  name  of  plagioclase.  This 
term  has,  however,  been  employed  since  to  include  both  albite  and  anor- 
thite, and  in  this  latter  sense  it  is  generally  used.* 

Tschermak,  indeed,  does  not  claim  this  theory  to  be  entirely  original  with 
himself,  for  he  remarks,  "  Dabei  verschweige  ich  jedoch  nicht,  dass  die 
Grundidee  dieser  Vereinfachung  keineswegs  neu  sei  und  ich  bemerke,  dass 
durch  die  friiheren  Bemiihungen  der  Forscher,  welche  eine  solche  Vereinfa- 
chung auf  chemischer  Basis  anstrebten,  also  durch  Sartorius  von  Walters- 
hausen,  Rammelsberg,  Scheerer,  der  Gedanke  endlich  so  weit  entwickelt 
wurde,  dass  Andere  wie  Delesse,  Hunt  denselben  als  keines  speciellen 
Beweises  bediirftig  hinstellten." 

Tschermak's  theory  was  variously  opposed  and  advocated,  and  on  one 
side  or  the  other  the  most  prominent  chemical  mineralogists  arranged 
themselves.  It  has  been  especially  discussed  by  Rammelsberg,  Rath,  Roth, 
Bunsen,  Peterson,  Streng,  and  others,  with  the  result  that  it  is  the  generally 
accepted  view  regarding  the  composition  of  the  feldspars. 

Tschermak's  theory  does  not  appear  to  be  well  understood  in  England 
or  America,  and  although  the  present  writer  recognises  his  liability  to  also 
misinterpret  it,  he  deems  it  right  to  point  out  some  of  these  differences  of 
opinion,  believing  that  in  the  end  it  will  lead  to  a  more  accurate  conception 
of  the  theory  than  now  seems  to  exist. 

Streng  later  offered  a  theory  for  the  feldspars,  in  which  he  held  that  they 
were  silicates,  in  which  the  Ca  partly  replaces  the  Na2,  and  R  the  Si2; 
claiming  that  there  were  only  two  principal  divisions;  1st,  the  potash  feld- 
spar, and  2d,  the  lime  soda  feldspar  —  the  latter  forming  a  number  of  varie- 
ties with  variable  composition.! 

*  Sitz.  Wicn.Akad.,  1864,  1.  (2)  pp.  566-613. 

f  Neucs  Jalir.  Min.,  1865,  411-434,  513-529;  1871,  598-618,  715-731. 


TIIK    FKI.IKSPAKS  .-    TSCHKKMAK'S   THEORY.  37 

Petersen  objected  to  Tschcrmak's  theory  on  the  ground  that  orthoclase 
feldspars  containing  soda  do  not  show  any  of  the  striations  peculiar  to  tri- 
clinic  feldspars,  which,  if  the  theory  is  correct,  must  be  mechanically  mixed 
with  the  soda-bearing  orthoclase;  also,  that  some  potash-bearing  plagioclases 
exhibit  no  trace  of  orthoela.se.* 

Professor  J  D.  Dana,  in  1867,  also  opposed  Tschermak's  theory,  holding 
that  the  variations  from  the  normal  analyses  were  caused  by, — 

(ft)  Incorrect  analyses. 

(6)  Impurities;  and  often,  mixtures  of  different  feldspars  through  inter- 
crystallization. 

(c)  Alteration ;  caused  either  (1)  by  the  infiltration  of  ordinary  waters, 
carbonated  or  not  —  the  rocks  containing  feldspars  having  been  exposed  to 
this  action  through  long  ages  past — or  (2)  through  the  same  process  aided 
by  mineral  ingredients  in  the  waters,  resulting  in  the  introduction  of  mag- 
nesia, oxide  of  iron,  etc.,  and  in  other  changes.! 

In  the  meanwhile  Tschermak's  theory  assumed  great  prominence,  and  in 
1874,  Dr.  T.  Sterry  Hunt  put  forward  the  claim  that  he  was  the  originator 
of  it.  In  support  of  this  assertion  he  quoted  from  a  published  abstract  of 
his  original  paper  (mtlc,  p.  35),  which  had  given  his  views  in  an  indefinite 
manner,  and  in  his  direct  quotation  from  this  abstract  a  hypothetical  state- 
ment was  altered  to  a  positive  one.  t 

As  pointed  out  in  the  preceding  pages,  Hunt's  theory  of  the  triclinic 
feldspars  is  nearly  the  same  as  Dana's  (b)  given  above.  Hunt  held  that 
they  were  indefinite,  variable,  mechanical  aggregates,  or  intercrystallizations; 
while  Tschermak  held  that  they  were  formed  by  isomorphous  molecular 
unions  in  definite  proportions.  Further,  Hunt's  theory  does  not  seem  to 
be  at  all  original  with  him. 

Yet  a  number  of  writers  have  acknowledged  Hunt's  claim,  presumably 
because  they  have  never  read  his  original  papers,  or  else  have  misunderstood 
Tschermak.  The  use  of  the  term  "  mixture  "  with  two  distinct  meanings 
—  1st,  for  mechanical  aggregation  (Hunt),  2d,  for  molecular  combination 
(Tschermak)  —  has  probably  added  to  the  confusion. 

*  Xcnes  Jnhr.  Min.,  1872,  pp  576-586  ;  Jour.  Prakt.  Chemie,  1873  (2),  vi.  200-212. 

t  AIIIIT.  Jour.  Sci.,  1867  (2),  xliv.  200,  399.     See  also  System  of  Mineralogy,  5th  cd.,  1868,  p.  336. 

t  Chcm.  Gcol.  Essays,  pp.  4-3S,  4«~ti5. 


38  CLASSIFICATION   BASED    ON   MINERAL   COMPOSITION. 

Amongst  those  who  have  acknowledged  Hunt's  claim  are  both  Danas,* 
Silliman,f  Leeds,  $  Rutley,§  Hawes,  ||  and  Fouque  and  Levy.  ^[ 

Edward  Dana  says  that  the  theory  "  was  offered  by  Hunt,  and  has  since 
been  developed  by  Tschermak ;  "  Rutley,  that  Hunt's  conclusions  are  almost 
identical  with  those  of  Tschermak ;  again,  James  D.  Dana,  mistaking  Hunt's 
views,  stated  of  the  latter,  "  In  the  view  .  .  .  with  regard  to  the  molec- 
ular relations  of  the  feldspars,  he  appears  to  have  anticipated  Tschermak  by 
ten  years ; "  while  Silliman  goes  so  far  as  to  say,  "  Here  will  be  found  devel- 
oped his  [Hunt's]  views  on  the  constitution  of  the  feldspars,  which  were 
some  years  later  adopted  without  acknowledgment  by  Tschermak."  Leeds 
appears  to  have  been  the  only  one  who  recognized  the  essential  difference 
between  the  indefinite  mechanical-mixture  view  adopted  by  Hunt,  and  the 
definite  molecular-union  theory  of  Tschermak ;  but  he  failed  to  see  the  logical 
conclusion  to  be  derived,  —  that  Hunt**  was  in  no  sense  the  originator  of 
Tschennak's  theory,  and  that  all  the  charges  of  appropriation  made  against 
the  latter  ought  to  be  entirely  withdrawn. 

In  1875,  Descloizeaux,  from  the  optical  properties  of  the  plagioclastic  feld- 
spars, concluded  that  andesite  was  an  altered  oligoclase,  but  that  labradorite 
and  oligoclase  are  distinct  species,  and  not  isomorphous  mixtures.  He  looked 
upon  their  optical  properties  as  opposed  to  Tschennak's  theory .tt  To  explain 
the  chemical  composition,  Descloizeaux  calls  attention  to  the  theory  of 
Friedel  and  others,  that  the  several  feldspars  differ  from  one  another  only 
in  their  proportions  of  silica,  forming  a  series  whose  common  difference  is 
Si02 :  e.  ff.,  anorthite  -j-  Si02  =  labradorite  ;  labradorite  -j-  Si02  =  andesite  ; 
andesite  -f-  Si02  —  oligoclase  ;  and  oligoclase,  -}-  Si02  =  albite. 

While  Descloizeaux  admits  that  the  composition  of  the  feldspars  may  be 
explained  as  well  by  Tschermak's  theory  as  by  Friedel's,  yet  he  holds  that 
the  latter  accords  better  with  the  optical  and  crystallographic  characters  of 
the  species. 

Vom  Rath,  on  the  other  hand,  is  of  the  opinion  that  the  chemical  consti- 
tution of  the  feldspars  is  most  satisfactorily  represented  by  Tschennak's 
theory,  and  holds  that  the  formation  of  the  intermediate  triclinic  feldspars 

*  Am.  Jour.  Sci.,  1875  (3),  ix.  102  ;  Text  Book  of  Mineralogy,  1877,  p.  297. 
t  Amcr.  Chemist,  1&74,  v.  106.  J  Amcr.  Chemist,  1877,  vii.  335. 

§  The  Study  of  Rocks,  1S79,  p.  95.  ||  Geol.  New  Hampshire,  1S7S,  iii.  parti,  p.  89. 

1[  Miner.  Microg.,  1879,  p.  200. 

**  Bull.  Mus.  Comp.  Zool.,  1881,  vii.  370-374,  443-454,  458,  459. 

ft  Ann.  Chimie  Physique,  1875  (5),  iv.  429-444;  Comptes  Keudus,  1875,  kxx.  364-371;  Neues  Jahr. 
Miu.,  1875,  pp.  279-284,  395-399. 


THE   FELDSPARS:    THEIE  COMPOSITION.  39 

by  the  molecular  union  of  albite  and  anorthite  is  an  established  law,  and 
not  a  mere  hypothesis.  He  states  that  the  supposition  that  the  difference 
of  composition  in  the  plagioclastic  feldspars  is  due  to  the  successive  addi- 
tion of  silica  molecules,  takes  no  account  of  the  replacement  of  lime  and 
soda,  which  is  so  intimately  associated  with  the  variation  in  the  amount  of 
silica.  Andesite,  he  holds,  is  distinct  from  oligoclase. 

In  1876,*  Descloizeaux  described  a  new  potash  feldspar  (microcline) 
which  is  tricliuic,  although  chemically  the  same  as  orthoclase.  This  dis- 
covery only  added  to  the  difficulties  and  confusion  in  the  feldspar  question. 
Mallard  and  Michel  Levy,  however,  taught  later  that  orthoclase  and  micro- 
cline were  the  same,  but  that  the  cross-twinning  had  become  so  fine  that  it 
was  no  longer  visible  in  polarized  light,  i.  e.,  the  laminae  were  excessively 
thin  —  so  much  so  as  to  cause  the  feldspar  to  appear  optically  homo- 

gcneous.t 

Extended  observations  were  later  made  by  Max  Schuster  on  the  optical 
characters  of  the  feldspars.  He  claims  that  these  characters  show  a  gradual 
change  or  transition  between  anorthite  and  albite,  pan  passu  with  the  varia- 
tion in  chemical  composition  ;  that  is,  each  definite  proportion  in  the  mix- 
ture of  anorthite  and  albite  gives  a  variety  whose  optical  properties 
approach  one  or  the  other  of  these  feldspars,  according  to  the  predomi- 
nance of  either.  From  the  optical  characters  of  any  feldspar  crystal, 
there  could  be  inferred  its  chemical  composition,  and  the  reverse.  He 
claims  that  Tschermak's  law  is  sustained  by  these  observations,  and  such 
seems  to  be  the  prevalent  opiuion.J  These  observations  of  Schuster  are 
in  accordance  with  those  of  Sennamont  on  Rochelle  salts.  §  They  not  im- 
properly may  lead  to  very  different  views  of  mineral  species  from  those 
commonly  held. 

From  the  above,  it  seems  clear  that  the  feldspars  are  either  species 
with  such  indefinite  boundaries  that  they  (the  feldspars)  cannot  be  defined 
with  any  accuracy,  or  else  they  form  a  continuous  scries  from  anorthite 
to  orthoclase.  In  either  case  it  is  improper  to  found  definite  groups  and 
specific  divisions  of  rocks  on  a  variable  and  indefinite  group  of  minerals, 
concerning  whose  nature  the  chemical  mineralogists  are  not  agreed. 

«  C'omptcs  Rendus,  1870,  kxxii.  885-S91  ;  Ann.  Cliimie  Physique,  1876  (.')),  ix.    433-499. 
f  Bnll.Min.Soc.  France,   1^79,  pp.  133-1:59  ;    Neucs  Jahr.  Min.,  1880,  i.  pp.  17-4,175;    Zcit.   Krvst., 
18SO,  iv.  632,  633. 

t  Sitz.  Wien.  Akad.,  1S79,  Ixxx.  (1),  192-200;  Miu.  MittU.,  18SO  (2),  iii.  117-284. 
§  Ann   Chimic  Physique,  1851  (3),  xxxiii.  429-437- 


40  CLASSIFICATION   BASED   ON   MINERAL  COMPOSITION. 

Even  supposing  the  species  were  well  established,  have  we  any  methods 
whereby  these  species  or  divisions  can  be  positively  discriminated  ? 

In  1876,  Descloizeaux  gave  a  method,  whereby  he  thought  the  differ- 
ent plagioclastic  feldspars  could  be  distinguished  from  one  another.  This 
method  required  a  thin  transparent  section,  either  cleaved  or  ground  par- 
allel to  the  plane  of  easiest  cleavage  (0,  OP,  001,  p)  —  the  triclinic  feld- 
spars being  as  a  rule  twinned,  so  as  to  show  color  bands  parallel  with  the 
plane  of  the  next  easier  (or  less  perfect)  cleavage.  The  sections  are 
placed  on  the  stage  of  the  polarizing  microscope,  with  the  color  bands 
parallel  to  any  diagonal  of  the  crossed  nicols  (plane  of  vibration  or 
plane  of  polarization)  ;  the  section  is  then  revolved  until  one  set  of  color 
bands  becomes  dark,  or  the  light  is  extinguished  in  them.  The  angle 
between  this  point  and  the  former  position  of  the  section  is  taken.  The 
section  is  then  revolved  in  the  opposite  direction  xintil  extinction  of  light 
takes  place  in  the  alternate  set  of  color  bands.  The  angle  between 
this  point  and  the  first  or  original  position  of  the  section  is  taken.  If 
the  section  is  properly  cleaved,  or  ground,  the  two  angles  observed  are 
equal.  By  experiment  on  feldspars  of  known  composition,  the  angles 
between  the  nicol  diagonal  and  the  extinguished  color  bands,  or  the  angle 
(double  the  others)  between  the  two  positions  in  which  the  alternate  bands 
are  rendered  dark,  have  been  determined ;  and  it  is  assumed  that  all  feld- 
spars having  the  same  angle  of  extinction  as  any  one  of  these  previously 
determined  angles  belongs  to  the  same  species  of  feldspar.  Descloizeaux 
held  that  this  supposed  fixity  of  optical  characters  was  opposed  to  Tscher- 
mak's  theory.* 

Prof.  R.  Pumpelly  endeavored  to  make  Descloizeaux's  method  practi- 
cally applicable  to  thin  sections  of  rocks,  which  he  did  in  the  following 
manner :  If  instead  of  cutting  sections  parallel  to  the  principal  cleavage 
they  should  be  cut  at  any  angle  with  that  cleavage  but  in  the  zone  0 : 
»l(p:h';  001:  100;  OP:  co  P  oo)  we  should  have  every  variation  of 
angle,  from  0°  up  to  the  maximum  for  that  feldspar.  In  a  thick  rock  sec- 
tion in  which  the  feldspars  are  cut  at  random,  it  is  necessary  first  to  ascer- 
tain whether  any  feldspar  section  has  been  cut  in  the  zone  0 :  ii.  This  is 
done  by  ascertaining  on  trial  if  the  extinction  in  the  alternate  color  bands 
takes  place  at  equal  angles  on  opposite  sides  of  the  nicol  diagonal.  If  it 
does,  the  section  of  feldspar  was  cut  as  required.  A  number  of  such  sections 

*  Comptcs  Rendus,  1876,  Ixxxii.  8S5-891 ;  Ann.  Chimie  Physique,  1876  (5),  k.  433-499. 


TIIK    m.DSl'ARS:    THEIR   DETERMINATION.  41 

are  usually  to  be  found  in  the  slide,  and  their  maximum  angle  is  taken 
as  the  index  of  the  feldspar.  In  actual  practice,  Professor  Pumpelly  took 
as  oligoclase  those  feldspars  of  which  several  individuals  in  a  rock  section 
•rave  angles  between  32°  and  36°;  as  labradorite,  those  between  36°  and 
62° ;  and  as  anorthite  those  over  62°. 

When  more  than  one  feldspar  is  present  in  the  slide,  only  that  one  can 
be  distinguished  which  has  the  highest  angle ;  and  this  may  be  the  minor 
or  subordinate  feldspar.  It  is  even  possible  for  a  single  crystal,  only,  of  one 
feldspar,  to  change  the  conclusion  as  to  the  rest  of  the  feldspars  in  the  sec- 
tion. Then,  again,  the  sections  examined  may  be  so  cut  as  to  give  a  lower 
angle  than  they  should  ;  therefore  the  observer  concludes  he  has  a  different 
feldspar  from  the  one  actually  present.  It  is  scarcely  possible  by  this 
method  to  distinguish  between  oligoclase  and  albite.* 

Professor  Pumpelly  was,  however,  anticipated  in  order  of  time,  in  the 
publication  of  this  method,  by  M.  Michel  Levy,  who  discussed  the  subject 
mathematically,  and  applied  the  principles  to  many  different  minerals.! 

That  the  work  of  both  Levy  and  Pumpelly  was  independent  and  original 
with  both,  can  be  inferred  from  the  fact  that  the  latter  asked  me  early  in 
the  year  1876  to  undertake  a  mathematical  discussion  of  this  subject,  in 
order  to  aid  his  experimental  work  which  he  was  then  upon.  The  mathe- 
matical portion  the  present  writer  had  then  neither  time  nor  inclination  to 
perform,  but  the  practical  work  of  Professor  Pumpelly  resulted  in  that 
method  of  determination  which  has  been  given  before.  Schuster's  results 
would,  however,  appear  to  render  such  determinations  of  but  little  value  at 
present. 

Dr.  George  W.  Hawcs  in  1881,  showed  that  the  common  method  of 
distinguishing  triclinic  from  monoclinic  feldspars  was  unreliable  in  certain 
cases;  for  labradorite  from  St.  Paul's  Island  and  Canada,  anorthite  from 
New  Hampshire,  and  oligoclase  from  Bodenmais,  exhibited  none  of  these 
supposed  distinguishing  features,  i.  e.  striation  in  common  and  polarized 
light.  J 

Amongst  the  methods  used  for  the  determination  of  the  feldspars,  as 
well  as  of  other  minerals,  is  the  micro-chemical  method  of  Dr.  E.  Boficky, 
which  consists  essentially  in  subjecting  the  specimen  to  the  action  of  lluo- 
silicic  acid,  hydrofluoric  acid  gas,  chlorine  gas,  etc.  ;  and  microscopically 

«  Proc.  Am.  Arad.  Sci.,  1S78,  xiii.  253-309;  Geol.  AVi>r.,  ISM),  iii.  30. 
f  Ann    Min,-,  \^',1  (7),  xii.  31)2-10!);  Comptcs  Remlus,  1878,  kxxvi.  316-348. 
J  1'r.c   Nat.  MILS.,  1S8I,  pp.  134-136. 

G 


42  CLASSIFICATION   BASED   ON   MINERAL   COMPOSITION. 

examining  the  crystals  produced,  under  proper  conditions.  This  is  simply  a 
method  of  making  qualitative  tests  upon  material  in  bulk  too  small  to  be 
tested  in  the  ordinary  way.* 

In  1876  Professor  J.  Szabo  published!  his  method  of  determining  feld- 
spars by  means  of  their  fusion,  reactions,  and  coloration  produced  in  the 
Bunsen  flame,  which  gave,  according  to  him,  a  means  for  estimating  the 
percentages  of  alkalies,  etc.,  in  the  specimen  examined. 

Still  a  third  method  is  from  the  crystals  formed  in  blowpipe  beads  under 
proper  conditions.  This  method  was  invented  by  Mr.  George  H.  Emerson 
in  1863,  t  and  later  expanded  by  Gustav  Rose,§  W.  A.  Eoss,||  and  H.  C. 
Sorby.^j  The  results  are  essentially  similar  to  Boricky's  method,  qualita- 
tive, but  can  be  used  with  small  fragments. 

The  last  and  most  important  method  is  that  of  separating  the  feldspars 
by  means  of  liquids  of  different  specific  gravities.  In  this  way  considerable 
material  of  a  certain  specific  gravity  can  be  obtained  for  chemical  analysis, 
and  its  nature  ascertained.**  All  these  methods  have  their  defects :  as,  for 
instance,  the  feldspars  which  give  character  to  the  rock  are  of  more  than 
one  species,  usually ;  they  contain  more  or  less  glass  and  mineral  impurities ; 
and  they  are  subject  to  alteration.  These  factors  change  their  specific 
gravity  and  chemical  relations,  and  make  the  determination  of  a  few  crystals 
of  but  limited  value  in  fixing  the  condition  and  character  of  the  remaining 
feldspars.  Of  all  the  methods  the  specific  gravity  one  promises  the  most, 
but  it  is  not  believed  at  present  to  lead  to  any  essentially  valuable  results 
in  determining  minerals  like  the  feldspars,  whose  very  species  are  so  inde- 
terminate. While  the  before-mentioned  methods,  and  many  others  not 
mentioned,  have  added  greatly  to  the  knowledge  of  minerals,  they  seem  to 
have  blinded  most  observers  to  the  general  characters  of  the  rocks  they  were 
studying. 

In  the  coarsely  crystalline  rocks  crystals  of  feldspar,  of  sufficient  size 
for  analysis,  can  often  be  obtained ;  but  that  analysis,  to  be  of  any  value, 
must  proceed  on  the  supposition  that  the  crystal  is  pure,  unaltered,  and 

*  Archiv  der  naturwisscnscliaftliohcn  Landesdurchforschung  Bolnnens,  1877,  iii-  5t1i  Abtli.,  pp.  1-SO. 

f  Ueber  erne  neue  Methode  die  Feldspatlie  aucli  in  Gcsteiucu  zu  bestimmen,  Budapest,  1876. 

J  Amer.  Jour.  Sci.,  1804(2),  xxxvii.  414,  415  ;  Proc.  Am.  Acad.,  1865,  vi.  476-494. 

§  Moiiatsb.  Berlin  Akad.,  1867,  pp.  129-147. 

||  Chemical  News,  18G8  (Amer.  Reprint),  ii.  74-76,  147,  148,  157-100,  196  ;  Pyrology  or  Fire  Chemis- 
try, London,  1875. 

f  Month.  Micro.  Jour.,  1809,  i.  349-352. 

**  Tlioulet,  Comptes  Rendus,  1S78,  Ixxxvi.  454-456;  Bull.  Min.  Soc.  France,  1879,  p.  17;  Church,  Min. 
Mag.,  1877,  i.  237,  238;  Goldschmidt,  Neues  Jahr.  Min.,  1881  (Bcilagc-Band),  pp.  179-238. 


THE  FELDSPARS   AS   A  BASIS  OF   CLASSIFICATION.  43 

typical  of  the  predominating  feldspar  in  the  rock ;  microscopic  analysis 
shows  that  the  larger  crystals  in  our  rocks  are  generally  abnormal,  often 
foreign  to  their  present  surroundings,  containing  numerous  inclusions,  some- 
times three  fourths  of  the  crystal  being  glass,  microlites,  etc.  If  a  thin 
section  is  prepared  before  the  chemical  analysis  is  made,  it  only  proves 
that  the  part  examined  is  pure  or  impure,  as  the  case  may  be,  offering  no 
proof  regarding  the  rest,  only  a  probability ;  further,  the  larger  crystals  are 
usually  the  subordinate  ones,  being  unlike  the  generality  in  the  mass  of  the 
rock.  This  method  is,  also,  inapplicable  in  the  cases  where  it  is  most  needed  ; 
in  the  fine-grained  and  compact  rocks,  which  contain  few  or  no  feldspars  of 
sufiicient  size.  The  larger  feldspars  are  most  subject  to  alteration,  passing 
from  the  basic  towards  the  acidic,*  some  becoming  greatly  changed  while 
the  smaller  crystals  are  untouched ;  yet  the  analyst  names  the  rock  from 
the  altered,  and  not  from  the  unaltered  feldspar,  —  euphotide,  for  instance.! 
The  secondary  formation  of  feldspars,  like  orthoclase  in  rocks,  adds 
greatly  to  the  difficulty  of  making  the  classification  dependent  upon  the 
kind  of  feldspar  present.  In  other  cases  the  feldspathic  material  is  seen 
to  be  largely  replaced  by  quartz  and  other  minerals  —  the  presence  of  the 
first  not  being  suspected  until  the  crystal  was  examined  under  the  micro- 
scope. The  twinned  character  of  the  triclinic  feldspars,  seen  both  in  com- 
mon and  polarized  light,  is  not  a  constant  character,  as  has  been  pointed 
out  before.  It  has  been  customary  to  regard  all  unstriated  feldspars  in 
basic  rocks  as  plagioclase,  cut  parallel  to  the  brachypinicoid,  but  in  the 
acidic  rocks  as  orthoclase.  Through  the  great  alteration  to  which  the 
feldspars  have  been  subject  in  the  older  rocks,  all  signs  of  twinning  have 
been  frequently  obliterated,  thereby  causing  such  crystals  in  granitoid 
rocks  to  be  classed  as  orthoclase.  J  The  chief  value,  therefore,  of  the 
optical  method  for  distinguishing  the  feldspars  is  apparently  to  deter- 
mine the  predominance  of  plagioclase,  or  of  orthoclase  ;  while  the  chief 
use  of  the  present  micro-mineralogical  study  of  the  feldspars  in  lithology 
is  the  determination  of  the  more  or  less  acidic  or  basic  composition  of  the 
rocks,  according  to  the  predominance  of  orthoclase  or  plagioclase  in  them. 
From  the  above  it  follows  that  a  systematic  classification  cannot  be  properly 
based  on  any  such  variable,  indeterminate  materials. 

*  Gco.  TV.  Hawes,  Geology  of  New  Hampshire,  iii.  part.  iv.  90-92. 

f  T.  Stem-  Hunt,  Am.  Jour.  Sci.  (2),  ]859,  xxvii.  336-319  ;  J.  D.  Dana,  ibid.  (3),  1878,  xvi.  340. 

J  Bull.  Mus.  Comp.  Z.M.I.,  1880,  vii.  55,  56. 


44  CLASSIFICATION   BASED   ON  MINERAL   COMPOSITION. 

The  Pyroxcne-Amiiliibole  Groups. 

In  the  ens.tatite-hypersthene-pyroxene-amphibole  group  of  minerals,  a 
similar  relation  seems  to  exist  as  in  the  feldspars,  and  a  like  variability. 

In  these  the  distinctions  are  founded  mainly  on  optical,  crystallographic 
and  cleavage  characters.  May  there  not  be  a  similar  relation  between  the 
orthorhombic  and  monoclinic  pyroxenes  as  there  is  between  the  different 
feldspars  ?  Specific  distinctions  between  rocks  have  been  based  solely 
on  a  difference  in  cleavage  in  minerals  otherwise  identical.  This  is  the 
case  with  augite  and  diallage,  which  thus  become  the  means  of  separating 
diabase  from  gabbro.  How  valid  this  cleavage  distinction  is,  may  be 
learned  from  the  fact,  that  the  cleavages  of  augite  and  diallage  are  found 
sometimes  united  in  a  single  crystal  of  pyroxene.  While  augite  has  been 
regarded  as  distinctive  of  the  augite-andesites,  basalts,  and  diabases,  more 
recent  observations  show  that  it  is  not  confined  to  any  one  species  of  rock, 
but  exists  in  every  species,  from  the  pallasites  to  the  rhyolites.  So,  too, 
it  was  regarded  as  entirely  characteristic  of  modern  or  younger  rocks,  but 
this  is  found  not  to  be  true.  This  belief  in  the  occurrence  of  augite  in 
modern  rocks  has  arisen  mainly  from  its  ready  alteration  to  viridite, 
chlorite,  hornblende,  biotite,  etc.,  which  would  thus  cause  it  nearly  or 
entirely  to  disappear  in  the  older  and  more  altered  rocks.  Again,  the 
probability  that  pyroxene  in  some  of  its  varietal  forms,  like  sahlite,  is  of 
secondary  origin,  increases  the  difficulty  of  employing  pyroxene  as  a  species 
character. 

In  the  case  of  hornblende  but  little  distinction  is  made  in  nomencla- 
ture, whether  the  mineral  is  foreign,  original,  or  secondary ;  but  in  all 
these  modes  of  occurrence  it  is  given  equal  value  in  classification.  As  a 
foreign  product  it  occurs  in  the  andesites,  the  augite  apparently  arising 
from  the  crystallization  of  the  dissolved  hornblende  material,  while  in  the 
older  forms  of  the  same  andesites  hornblende  occurs  as  a  secondary  product, 
after  both  the  foreign  hornblende  and  original  augite.  But  the  same  rock 
is  given  three  different  names,  according  to  the  predominance  of  augite, 
foreign  hornblende,  or  secondary  hornblende.  This  is  done,  however,  uncon- 
sciously by  lithologists,  since  they  do  not  practically  make  these  mineralog- 
ical  distinctions.  The  writer  has  seen  two  sections  taken  from  the  same 
hand  specimen;  one  of  which  pronounced  the  rock  a  diabase,  the  other  a 
diorite. 


TIIF.   MIXERALOGICAL   NOMENCLATURE  OF   ROCKS.  45 

Of  other  minerals,  mica  occurs  in  a  series  of  species  like  the  feldspars, 
and  in  rocks  is  found  in  all  three  forms  —  foreign,  indigenous,  and  second- 
ary ;  while  chlorite  and  epidote  are  probably  always  secondary.  From 
this  it  would  appear  that  they  are  not  suitable  to  designate  species. 

Mincralotfical  Nomenclature  of  Rocks. 

As  the  result  of  my  study,  I  have  been  obliged  to  regard  classification 
based  on  mineralogy,  unless  it  be  for  some  varietal  subdivisions,  as  impracti- 
cable, because  it  is  not  a  natural  but  an  artificial  method ;  a  system  that 
requires  constant  change  and  readaptation ;  and  further,  one  that  is  based 
too  much  upon  theory,  individual  judgment,  and  weight  of  authority;  a 
system  that  admits,  even  requires,  the  "dumping"  of  rocks  into  certain 
places  without  the  slightest  regard  to  their  relations  of  any  kind,  except 
it  be  that  they  hold  one  or  at  most  a  few  minerals  in  common.  This  rela- 
tion is  often  vitiated  by  the  observer's  not  taking  into  account  whether 
these  minerals  are  natural  crystallizations  in  the  rock,  foreign,  or  secondary 
products. 

When  classification  is  based  on  structure  it  usually  separates  the  rock 
into  distinct  species  according  as  it  is  glassy,  partly  glassy,  crystalline,  or 
porphyritic.  That  these  distinctions  are  valueless,  the  writer  thinks,  fol- 
lows from  the  fact  that  the  same  rock  mass  may  show  all  these  cases ; 
dikes  often  being  glassy  and  non-porphyritic  on  the  edges,  and  crystalline 
and  porphyritic  towards  the  middle.  The  granitic  structure  indicates  pro- 
bably a  certain  depth  at  the  time  of  crystallization,  but  that  this  may 
practically  be  slight  has  been  shown  by  the  lava  flows  of  Keweenaw  Point, 
some  of  which  are  fine-grained  on  the  surface,  and  coarsely  crystalline 
(granitic  or  diabasic)  towards  the  base. 

SECTION  VI.  —  Naming  Rocks  according  to  the  Geological  Age. 

Tins  question  has  been  so  well  discussed  by  Allport,*  Dana  t  and  others, 
that  but  little  needs  be  said  upon  the  subject  here.  Chemical,  microscopi- 
cal, and  geological  evidence  all  point  to  the  fact  that  this  division  is  not  a 
natural  one ;  and  so  far  as  my  work  has  gone,  the  original  characters  of  the 

«  Geological  Magazine,  1S71  (1),  viii.  249;  1S75  (2),  ii.  583;  Quart.  Jour.   Geol.  Soc.,  1874,  xxx. 
529. 

t  Amer.  Jour.  Sci.,  1S78  (3),  xvL  336. 


46  NAMING   ROCKS   ACCORDING   TO   THEIR  GEOLOGICAL   AGE. 

rocks  are  the  same  from  the  earliest  times  to  the  present.  Other  things 
being  equal,  the  older  rocks  are  more  altered ;  but  as  other  things  are  not 
equal,  no  abrupt  line  can  be  drawn  at  the  tertiary  age,  as  is  now  generally 
done ;  no  characters  exist  whereby  it  can  be  done,  and  the  line  must  remain 
an  arbitrary  one.  Alteration  produces  characters  in  the  rocks  that  can  be 
used  to  indicate  their  greater  age,  or  greater  alteration  —  terms  which  are 
not  synonymous,  although  usually  taken  to  be.  The  subject  can,  perhaps, 
be  best  formulated  as  follows :  all  rocks  upon  the  earth's  surface  undergo 
alteration,  and  when  exposed  to  the  same  conditions  this  is  proportionate 
to  the  age.  It  is  the  unquestioned  duty  of  the  petrographer  to  study  these 
changes,  and  starting  from  the  least  altered  rock  trace  the  continuous  series 
to  the  most  altered  one  of  that  kind.  Such  a  system  of  work  has  been 
attempted  here,  so  far  as  time  and  means  have  permitted. 

The  presence  or  absence  of  fluidal  cavities,  which  has  been  urged  as  a 
distinction  between  tertiary  and  pre-tertiary  rocks,  seems  to  be  related  more 
"to  depth,  and  the  conditions  to  which  the  rocks  have  been  exposed  since 
consolidation,  than  to  age.  The  modern  volcanic  rocks  are  but  the  froth 
of  an  eruption,  compared  with  the  massive  eruptions  that  have  taken  place 
in  past  time.  The  specimens  collected  are  generally  of  a  surface  nature, 
and  would  allow  the  very  ready  escape  of  the  inclosed  vapors ;  while  at 
some  depth  the  escape  could  not  take  place  as  readily.  Our  older  rocks 
have  in  general  suffered  more  denudation,  and  therefore  are  more  likely 
to  contain  fluid  inclusions.  Should  it  be  shown  that  these  fluid  cavities  are 
in  part,  or  entirely,  of  posterior  formation  to  the  rock,  as  has  been  urged 
by  Vogelsang,*  and  shown  by  Julien  to  be  so  in  one  case,t  it  would  require 
a  new  interpretation  to  be  placed  upon  these  and  upon  their  occurrence. 
My  work  would  indicate  that  while  part  of  the  fluidal  cavities  are  origi- 
nal, some  are  posterior  to  the  consolidation  of  the  rock.  A  more  fatal 
objection  to  their  use  in  separating  tertiary  from  pre-tertiary  rocks  is  the 
finding  of  fluidal  cavities  in  undoubted  tertiary  and  post-tertiary  rocks.  $ 
Why  quartz  should  be  the  mineral  chosen  to  found  this  distinction  upon, 
and  other  minerals  containing  fluid  inclusions  in  lavas  should  be  ignored, 
is  a  difficult  thing  to  understand. 

The  older  rocks  are,  as  a  rule,  entirely  crystalline/ a  condition  arising  in 

*  Philosophic  der  Geologie,  p.  155. 
t  Am.  Quart.  Microscopical  Jour.,  1879,  i.  103-115. 

£  H.  C.  Sorby,  Quart.  Jour.  Geol.  Soc.,  1858,  xiv.  484 ;  Franz  Zirkel,  Microscopical  Petrography,  vi. 
142,  156,  157,  104,  106,  167,  170,  205;  Zeit.  Dcut.  geol.  Gcsell,  1S68,  xx.  117,  132. 


METHODS   OF   CLASSIFICATION.  47 

part  from  the  alteration  of  the  non-crystalline  materials,  and  in  part  from 
the  fact  of  the  more  or  less  denudation  which  they  have  suffered.  When 
Iniried  enough  to  allow  of  a  more  or  less  slow  solidification,  the  tendency  is 
to  form  a  completely  crystalline  structure,  approaching  more  and  more  to 
the  granitic.  While  the  chief  portion  of  the  granitic  structure,  like  that 
scon  in  gabbros,  some  diabases  and  diorites,  true  granites  and  syenites,  is 
indigenous,  all  does  not  seem  to  be  so,  and  great  depth  does  not  appear  to 
be  indispensable  ;  the  only  requirement  seems  to  be  slow  solidification. 

SECTION  VII.  —  MdJiods  of  Classification. 

THE  framework  of  any  descriptive  or  systematic  science  is  its  classifica- 
tion, and  upon  it  depends  much  of  the  value  and  suggestiveness  of  the  work. 
It  hence  becomes  a  most  important  and  vital  point  that  the  classification 
used  shall  be  as  correct  as  possible.  The  common  classifications  of  rocks  are 
well  known  to  be  artificial,  and  the  writer  has  found  them  unsatisfactory  in 
his  work.  Instead,  therefore,  of  endeavoring  to  invent  a  new  one,  he  has 
striven  to  discover  the  laws  and  principles  of  the  natural  system,  so  far  as 
the  rocks  studied  might  enable  him  to  do  so. 

In  studying  rocks  by  any  system,  two  methods  are  open  to  the  observer. 
One  is  to  simply  describe  the  characters  of  the  minerals  in  the  rock,  thus 
making  the  minerals  the  principal  object,  and  the  rock  the  subordinate  one. 
In  this  case  lithology  becomes  simply  a  mineralogical  study,  and  the  litholo- 
gist  a  mineralogist,  who  looks  upon  his  rocks  as  small  mineral  cabinets,  not 
realizing  that  the  minerals  are  for  the  most  part  changing  and  changeable, 
and  that  the  true  method  is  to  trace  the  history  and  variations  of  the  rock 
as  manifested  in  its  mass  and  its  constituents. 

The  other  method  is  to  study  the  rocks  for  the  purpose  of  determining 
their  natural  relations,  the  various  changes  they  have  undergone,  and  the 
characters  by  which  they  may  be  known  in  all  these  various  alterations. 
In  this  the  rock  is  the  unit,  the  paramount  object,  and  the  mineral  the 
subordinate  quantity.  From  this  point  of  view  the  minerals  in  a  rock 
answer  to  the  teeth  and  bones  in  an  animal  —  very  important,  but  not 
superior  in  value  to  the  animal  as  a  whole.  In  a  rock  the  mineral  is  the 
accident,  it  may  or  may  not  exist ;  and  when  the  rock  is  entirely  composed 
of  crystallized  minerals,  they  should  be  used  as  the  teeth  and  bones  are  used 
in  determination,  when  the  zoologist  has  them  alone  in  his  specimen  —  in 


48  A   NATURAL   CLASSIFICATION   OF   ROCKS. 

subordination  to  his  general  knowledge  of  animal  structure.  The  subor- 
dinate relation  of  the  mineral  to  the  rock  is  more  obscure  than  the  same 
relation  of  the  bones  to  the  animal  as  a  whole,  since  it  is  true  that  the 
mineral  makes  up  the  whole  of  the  majority  of  rocks.  The  subordination  of 
the  crystalline  minerals  to  the  rock  unit  has  been  above  thus  strongly 
insisted  upon  since  the  opposite  view  seems  to  be  taken  by  many  litho- 
logists,  who  appear  to  study  as  microscopical  mineralogists,  instead  of  work- 
ing as  lithologists  proper. 

If  it  is  possible  to  find  the  principles  of  the  natural  classification  of  rocks 
they  ought  to  be  applicable  to  any  rock,  whatever  may  be  its  age  and  condi- 
tion. By  the  natural  classification  of  rocks  is  meant  that  system  which  will 
place  together  those  forms  nearest  allied  in  their  general  characters,  composi- 
tion, structure,  and  origin,  when  the  rock  as  a  whole  is  considered,  and  not 
certain  of  its  characters  only.  The  present  artificial  classifications  of  rocks 
pick  out  certain  mineralogical  characters,  and  render  the  rock  characters  sub- 
ordinate to  them.  These  classifications  are,  to  a  certain  extent,  natural,  and 
afford  a  convenient  method  of  arrangement,  requiring  on  the  part  of  the 
lithologist  who  follows  them  simply  skill  in  the  determination  of  minerals. 
The  method  works  well  in  some  places,  in  others  it  masses  together  a  most 
heterogeneous  collection  of  rocks  in  a  single  species  —  causing  some  rock 
names,  like  diorite  for  instance,  to  remind  one  of  the  old  use  of  the  term 
schorl  in  mineralogy.  The  employment  of  the  minerals  alone  to  determine 
the  rock  species  is  like  Linnosus's  use  of  the  stamens  and  pistils  in  botani- 
cal classification  —  a  convenient  but  artificial  system.  One  in  objecting  to 
the  sexual  system  in  botany  does  not  reject  the  use  of  the  stamens  and  pistils 
in  classification,  but  he  does  object  to  their  over-riding  all  other  characters. 
They  are  to  have  their  just  and  proportionate  weight,  but  no  more.  So,  too, 
in  lithology  the  minerals  in  rocks  hold  a  similar  relation  to  them  that  the 
sexual  organs  do  in  plants  —  they  may  comprise  all  or  but  little  of  the  rock 
or  plant.  Minerals  are  entitled  to  their  just  and  proportionate  weight  in 
rock  classification  but  no  more;  they  are  not  to  be  allowed,  in  my  judg- 
ment, to  become  superior  to  the  rock  itself.  No  single  character  should  be 
allowed  to  over-ride  all  the  others,  that  is :  the  pi'esence  or  absence  of  a 
single  mineral  ought  not  to  remove  a  rock  from  the  species  to  which  all  its 
other  characters  assign  it.  In  the  current  classifications  it  frequently  hap- 
pens that  the  name  given  to  the  rock  depends  upon  the  particular  portion 
of  the  hand-specimen  from  which  the  microscopic  section  was  taken. 


MODERN   METHODS   OF   CLASSIFICATION   CHARACTERIZED.  49 

The  present  lithological  methods  of  classification  can  best  be  character- 
ized, in  a  homely  way,  by  supposing  that  there  were  placed  in  the  hands  of 
a  zoiilogist  a  great  number  of  specimens  of  one  species  of  some  carnivorous 
animal,  in  every  condition,  from  a  fresh  state  to  that  of  an  advanced  stage 
of  decomposition ;  also  of  those  of  the  same  species  that  had  lived  during 
distinct  periods  of  time,  as  well  as  of  those  -that  had  lived  for  different 
lengths  of  time.  With  these,  too,  let  there  be  given  to  the  zoologist  a 
number  of  packages  of  the  bones  of  this  animal,  part  of  the  bones  having 
been  worn  and  part  nnworn. 

Now,  imagine  this  zoologist  naming  as  new  species  every  specimen  more 
decomposed  than  a  preceding  one ;  as  new  species,  those  which  showed 
different  products  of  decomposition  ;  as  new  species,  those  that  gave  any 
variation,  through  that  decomposition,  upon  chemical  analysis  —  as  for 
instance,  one  and  forty-seven  one  hundredths,  or  even  nine-twentieths  of 
one  per  cent.  Continuing,  let  it  be  supposed  that  our  zoologist  makes  new 
species,  or  at  least  varieties,  out  of  all  specimens  in  which  he  finds  any  teeth 
or  bones  of  other  animals  which  have  been  swallowed ;  changing  the  species 
or  variety  as  often  as  the  inclosed  fragments  differ ;  creating  new  species 
out  of  all  that  have  lived  for  different  lengths  of  time ;  new  species  out  of 
those  whose  bones  are  fractured  crosswise,  as  distinct  from  those  whose  bones 
are  broken  lengthwise ;  new  species  out  of  the  distinct  packages  of  frag- 
ments ;  new  species  according  as  these  fragments  are  worn  or  angular ; 
jilso,  above  and  beyond  all,  fixing  an  arbitrary  date,  and  demanding  that 
all  the  specimens  of  this  animal  that  had  existed  prior  to  that  time  should 
be  held  as  distinct  species,  and  in  general  of  different  origin  from  those  that 
were  of  a  later  period.  Suppose,  too,  that  in  addition,  our  zoologist  should 
maintain  that  some,  or  all,  of  the  animals  submitted  to  him  were  made 
out  of  the  remains  of  their  defunct  ancestors,  by  a  species  of  fermen- 
tation ;  also,  that  this  creative  chemical  action  was  brought  about  by  the 
deposition  of  the  more  recent  remains  upon  the  older,  and  that  then  the 
older  forms  successively  came  from  beneath  and  lay  down  on  top,  thus  pro- 
ducing a  perpetual  cycle.  Let  the  reader  suppose  all  this  and  he  will  gain 
some  idea  of  the  principles  and  methods  commonly  employed  in  lithology,  as 
well  as,  in  a  greater  or  less  degree,  in  chemistry  as  applied  to  rocks. 

This  is  no  mere  fancy  sketch,  but,  so  far  as  can  be  done  by  taking  an 
illustration  from  a  distinct  science,  shows  some  of  the  principles  of  lithology 
a<  taught  t<j-du>/,  and  some  of  the  methods  upon  which  rocks,  even  now,  are 
classified. 


50  REMARKS   ON   CLASSIFICATION. 

Of  course,  every  degree  of  skill  exists  in  the  applications  of  any  classifi- 
cation, and  many  men,  even  with  erroneous  principles,  succeed  better  than 
others  do  who  work  with  correct  ones.  In  this,  however,  it  is  a  question  of 
methods  and  not  of  men ;  if  it  were  the  latter,  then  no  discussion  would  be 
possible,  since  the  older  and  more  experienced  would  always,  and  justly, 
claim  the  right  to  have  their  views  followed.  Since  it  is  a  question  of 
science  and  methods,  it  is  often  true  that  some  young  and  fresh  observer 
may,  starting  from  the  ground  gained  by  others,  push  on  a  little  way  beyond 
them ;  this  too,  when  he  ma'y  not  "have  a  tithe  of  the  .ability  of  the  others ; 
and  it  is  not  to  be  taken  as  presumption,  if  he  endeavors  to  hold  and  point 
out  the  ground  he  thinks  he  has  gained. 

The  principles  and  methods  employed  herein  were  essentially  enun- 
ciated by  me  in  1879,*  the  chief  changes  being  the  greater  extension  of  the 
subject,  owing  to  further  investigations ;  and  these  principles  have  been  used 
by  myself  and  my  students  in  papers  published  since.  Owing  to  the  con- 
densed or  abstract  form  of  the  first  publication,  it  seems  to  have  been  but 
little  understood  by  lithologists  working  in  the  mineralogical  method  of  rock 
classification ;  but  it  is  hoped  that  the  publications  made  since  then,  includ- 
ing this,  will  make  my  meaning  sufficiently  clear.  One  thing  is  certain,  that 
unless  a  lithologist  has  had  an  extensive  range  of  study  of  both  the  unal- 
tered and  altered  forms  of  rocks,  and  seen  their  relations  in  the  field,  such 
understanding  will  be  difficult.  Bearing  upon  this,  it  is  to  be  pointed  out 
that,  outside  of  the  rocks  from  a  few  volcanoes  in  Europe,  every  rock  that  I 
have  seen  from  that  country  is  altered,  to  a  greater  or  less  degree ;  but  the 
European  classifications  are  chiefly  based  on  such  altered  rocks.  Hence,  a 
mineralogical  classification  would  naturally  be  adopted  there,  and  will  be 
tenaciously  held  to.  A  lithologist  who  is  dependent  on  the  material  that 
Europe  alone  can  furnish  him,  has  not  the  means  at  his  command  of  judging 
accurately  regarding  the  basis  of  much  of  my  work,  which  has  been  founded 
upon  much  fresher  and  less  altered  specimens  than  his.  The  most  that  I 
can  hope  to  do,  however,  is  to  call  attention  to,  and  point  out,  that  which 
seems  a  better  way  than  the  one  at  present  followed.  To  perfectly  express 
the  natural  system  of  rocks  requires  a  universal  knowledge  of  them — a 
knowledge  that  it  is  not  given  to  any  man  to  possess. 

No  definite  scheme  of  classification  can  be  laid  down  in  the  beginning  ; 
it  must  result  from  the  study  of  all  available  specimens,  and  be  the  best 

*  Bull.  Mus.  Comp.  Zool.,  1879,  v.  275-287- 


THE   TRUE   PRINCIPLES   OF   CLASSIFICATION.  51 

arrangement  according  to  their  natural  affinities  that  can  be  ascertained 
by  that  study.  Future  studies,  discoveries  of  new  rocks,  and  other  causes 
are  liable,  in  this  science  as  in  botany  and  zoology,  to  change  the  particular 
arrangement;  but  the  principles  and  methods,  so  far  as  they  are  natural,  will 
remain  the  same. 

The  natural  method  is  sufficiently  elastic  to  allow  of  the  incorporation 
of  whatever  new  divisions  future  investigations  may  require ;  it  can  never 
expect  to  be  fixed  and  rigid,  until  the  sum  of  human  knowledge  shall  be 
complete.  These  changes  will  result  simply  in  removing  the  artificial  por- 
tions which  imperfect  knowledge  has  incorporated  with  it,  and  bring  the 
classification  nearer  and  nearer  to  the  perfect  natural  system.  If  none  of 
the  system  here  adopted  is  natural,  then  all  will  in  time  be  removed. 

The  important  principle  that  underlies  the  natural  classification,  as  here 
advocated,  is  the  belief  that  the  older  rocks  now  classed  as  disliiicl  species  are 
rocks  that  oiice  were  identical  with  their  younger  prototypes  —  the  present  differences 
In  in/I  due  to  alteration,  and  conditions  of  crystallization. 

Standing  next  to  this,  is  the  belief  in  the  chanc/cableness  of  the  mineral  con- 
stttnli'n)  of  the  rocks,  and  the  feeling  that  no  classification  should  be  placed 
entirely  on  so  uncertain  a  foundation. 

As  a  deduction  from  the  preceding  discussion,  the  following  statements 
may  be  taken  as  guides  in  describing  and  classifying  our  rocks :  — 

SECTIOX  VIII.  —  The  Principles  of  Classification. 

1.  IK  the  study  of  rocks,  we  should  begin  with  the  younger  and  glassy 
state,  and  follow  the  gradations  step  by  step  to  the  most  crystalline  one  in 
the  series  —  from  the  least  altered  to  the  most  altered  forms  —  tracing  every 
change,  and  studying  their  history  in  their  tufaceous,  poroditic,  metamorphic, 
or  any  other  state  in  which  they  or  their  remains  can  exist. 

2.  Any  rocks  that  can  be  followed   in  this  way  between  certain  limits, 
whatever  may  be  the  changes  they  have  undergone,  form  a  species.      In 
every  shape  they  should  be  retained  under  the  specific  name ;  the  various 
modifications,   when  of  sufficient  importance,  being  regarded  as  varieties, 
and  named  as  such. 

3.  All  the  petrological,  lithological,  and  chemical  characters  should  be 
used  in  determining  rock  species ;  that  is,  the  rock  as  a  whole  and  in  all 
its  relations  should  be  considered. 


52  THE   TRUE   PEINCIPLES   OF  CLASSIFICATION. 

4.  The  classification  should  be  a  natural  one,  therefore  empirical,  embody- 
ing all  known  characters  of  the  rocks.    A  natural  mineralogical  classification 
of  rocks  is  an  impossibility,  as  it  is  based  on  part  of  the  characters  only  — 
characters  which  are  unstable.     Minerals  may  serve  for  the  establishment  of 
varieties,  but  not  of  species. 

5.  Geological  age  has  no  value  in  the  classification  of  rocks,  and  is  not  to 
be  employed  except  incidentally  in  varietal  forms. 

6.  The  addition  of  new  names  in  any  science,  unless  they  are  absolutely 
necessary  for  its  advancement,  is  a  detriment :   the  needed  names  should  be 
taken  from  those  now  in  use,  so  far  as  possible,  and  they  should  be  employed, 
as  nearly  as  may  be,  in  their  most  approved  sense  ;  when  they  belong  to 
varieties  they  should  be  defined  as  such,  and  placed  in  their  natural  relations 
to  the  species  of  which  they  form  a  part. 

7.  In  the  classification  of  rocks,  the  original  characters  ought  to  hold 
priority  over  any  of  the  secondary  ones ;  and  they  should  give  name  to  the 
rock,  and  decide  its  relations,  so  long  as  they  exist  in  a  determinable  state. 
If  necessary,  or  convenient,  variety  names  or  adjective  terms  can  be  added, 
to  mark  the  special  peculiarities  of  secondary  or  other  origin  —  but  only  in 
especially  important  cases. 

8.  If  a  rock  is  found  to  have   the  characteristics  of  any  species  as  its 
prevailing  characters,  it  should  be  referred  to  that  species. 

9.  Chemical  analysis  alone,  as  a  general  rule,  is  insufficient  to  furnish 
data  for  naming  a  rock,  since  it  is  to  be  expected  that  rocks  originating  in 
different  ways  should  have  the  same  composition. 

10.  The   relation  of  a  rock    to  its   associated  rocks  in  the  field  is  the 
principal  criterion  for  determining  its  origin,  especially  in  the  altered  rocks. 

11.  Association  alone  is  an  insufficient  guide  in  determining  the  origin 
of  a  rock. 

12.  The  origin  of  a   rock  should  have  an  important  bearing  upon  its 
classification. 

13.  The  classification  should  be  the  exponent  of  some  general  law,  which 
should  embody  all  that  is  known  at  present  of  the  rocks,  and  give  promise 
for  the  future. 


CLASSIFICATION   IN   L1THOLOGY.  —  GENERAL   CONCLUSIONS.  53 


SECTION  IX. —  General  Conclusions  in  Regard  to  Systems  of  Lithological 

Classification. 

THE  general  results  and  bearing  of  the  preceding  can  be  briefly  summa- 
rized as  follows :  — 

As  is  claimed  for  the  organic  world,  so  there  is  for  the  inorganic  universe 
a  universal  law  of  evolution  or  development  expressed  by  the  phrases: 
<l<'</r<t<lnlion  and  dissipation  of  energy,  the  passage  of  the  unstable  towards  the  more 
.^lnli/i'  <-<ntil!tion, —  a  law  under  which  the  universe  has  moved  forward  or 
"  run  down  "  from  the  beginning,  and  under  which  its  course  will  continue 
uniformly  to  the  end. 

True  and  natural  classification  and  work  ought  to  give  expression  to  that 
law  and  conform  to  it,  and  the  classification  and  arrangement  herein  fol- 
lowed is  an  effort  towards  that  end.  In  accordance  with  this,  petrography 
seems  to  demand  a  former  liquid  globe  and  one  whose  interior  portions  are 
either  now  liquid,  or  in  such  a  condition  that  they  can  readily  become  so. 
If  the  so-called  physical  and  mathematical  demonstrations  of  the  earth's 
solidity  be  examined,  it  will  be  found  that  they  have  been  based  on  certain 
hypothetical  globes,  of  a  constitution  unlike  that  of  the  earth,  and  therefore 
not  applicable  to  it,  but  to  the  hypothetical  globes  only.  On  examining 
the  claim  that  the  materials  of  which  the  earth's  interior  is  supposed  to  be 
composed  would  tend  to  solidify  under  pressure,  because  they  contract  in 
passing  from  the  liquid  to  the  solid  state,  it  is  found  that  the  best  and  more 
recent  observations  which  compare  the  relation  of  the  solid  and  liquid  form 
—  both  taken  at  a  temperature  near  the  melting  point  —  either  prove  or 
render  it  probable  that  iron  and  the  various  rock  materials  which  are 
believed  to  compose  the  itt/ra-sediraentary  portion  of  the  earth  expand  on 
passing  from  the  liquid  to  the  solid.  Hence,  according  to  Thomson's  law, 
pressure  would  tend  to  render  the  earth's  interior  liquid  instead  of  solid. 

The  alleged  sinking  of  the  earth's  crust  to  the  earth's  centre  could  not, 
according  to  the  above,  take  place ;  since  the  solid  would  be  lighter  than  the 
liquid  portion  in  contact  with  it.  But  if  the  crust  were  heavier  it  could  not 
sink  far,  unless  the  earth  was  of  homogeneous  material ;  but  since  we  know 
it  to  be  heterogeneous  —  the  materials  varying  also  in  specific  gravity  — 
the  crust  on  sinking  would  soon  meet  with  material  of  higher  specific 
gravity,  which  would  prevent  any  further  subsidence.  So,  too,  the  heat 


54  CLASSIFICATION   IN    LITHOLOGY.  —  GENEEAL  CONCLUSIONS. 

imparted  to  the  sinking  crust  would  make  it  lighter,  while  the  viscosity  of 
the  still  liquid  matter  would  retard  the  descent. 

Since  we  may  accept  that  which  the  facts  of  geology  and  petrography 
appear  to  indicate  —  an  earth  with  a  liquid  interior  —  we  may  also  hold,  in 
accordance  with  observed  petrographical  facts,  that  all  rocks  originally  came 
from  the  cooling  molten  material  of  the  globe,  and  that  the  sedimentary 
and  chemical  rocks  have  resulted  from  the  disintegration  of  that  material, 
while  all  eruptive  or  volcanic  (including  plutonic)  forms  were  derived  from 
that  material  which  either  had  never  solidified  or  had  been  reliquefied;  but 
they  were  not  formed  from  either  chemical  or  sedimentary  deposits. 

From  this  it  would  naturally  follow  that  regions  of  crystalline  rocks  are, 
as  a  rule,  regions  in  which  eruptive,  or  mixed  eruptive  and  sedimentary 
agencies  have  prevailed;  and  these  rocks  are  of  every  geological  age  — 
meaning,  by  eruptive  agencies,  the  original  and  secondary  results  of  a  cool- 
ing globe,  including  thermal  waters.  The  original,  including  eruptive,  rock 
materials  appear  to  be  the  same  for  each  species,  no  matter  from  what  region 
they  may  have  come.  Hence  the  same  principles  should  be  employed  in 
classifying  them ;  and  the  classification,  to  be  natural,  ought  to  express  their 
relationships. 

This  natural  classification  should  be  based  on  all  the  characters  of  the 
rocks,  taken  together.  It  must,  of  course,  be  an  empirical  one,  as  in  zoology 
and  botany,  and  ascertained  by  studying  all  known  forms,  considering  all 
their  relations,  and  arranging  them  according  to  their  petrological,  litho- 
logical,  and  chemical  characters.  With  but  one  exception,  all  classifications 
in  use  at  the  present  time  are  confessedly  artificial ;  as  can  be  readily  seen 
by  examining  those  proposed  by  Naumann,  Blum,  Von  Cotta,  Zirkel,  Dana, 
Lang,  Lasaulx,  Rosenbusch,  Roth,  and  many  others.  The  exception  is  the 
classification  of  Richthofen,  which  however  applies  only  to  the  modern  vol- 
canic rocks.  This,  although  starting  with  many  natural  principles,  has  been 
rendered  highly  artificial  in  its  practical  applications.  The  classifications  of 
rocks  have  usually  been  based  on  part  of  the  characters  only,  to  the  exclu- 
sion of  others ;  as,  for  instance,  on  age,  structure,  mineral  composition,  and 
upon  almost  every  part  of  the  rock  separately,  but  not  upon  the  rock  as  a 
unit.  In  the  schemes  based  on  the  contained  minerals,  but  little  attention 
has  been  paid  to  the  question  whether  the  minerals  were  foreign,  original, 
or  secondary  products  in  the  rock.  So  long  as  the  same  minerals  existed 
there,  no  matter  how  diverse  their  origin,  all  rocks  containing  them  were 


CLASSIFICATION    IX   LITHOLOGY.  —  GENERAL  CONCLUSIONS.  55 

called  by  the  same  name.  Again,  if  the  mincrnlogical  classification  is  adopted 
it  is  found  that  the  species  of  feldspar,  which  form  the  corner  stone  of  that 
classification,  and  their  relations,  have  not  been  definitely  settled;  and  let 
the  method  of  determination  adopted  be  .what  it  will,  they  cannot  be  accu- 
rately and  surely  distinguished  from  one  another;  therefore  no  system 
should  be  placed  on  such  an  uncertain  foundation.  Such  classifications  cor- 
respond to  the  Linnean  artificial  botanical  classification,  and  hold  about  the 
same  relations  to  the  natural  classification  of  rocks  as  that  does  to  the 
natural  classification  of  plants.  The  greater  number  of  rocks  separated  by 
these  classifications  into  distinct  species  seem  to  be  mere  varietal  forms  of 
certain  natural  species  —  the  variation  being  due  to  alteration,  or  some 
change  in  condition.  Distinction  should  be  made  between  superficial 
weathering  and  the  chemical  and  molecular  changes  that  go  on  in  all 
eruptive  rocks,  after  consolidation  and  exposure  to  the  action  of  infiltrating 
waters ;  that  is,  changes  in  the  rock-rnass  as  a  whole  —  a  change  from  an  un- 
stable to  a  more  stable  condition,  a  loss  of  energy.  It  is  believed  that  to 
these  changes  is  due  in  general  the  difference  now  observable  between  the 
ancient  and  modern  eruptive  rocks  of  the  same  types.  In  other  words,  to 
these  changes  is  due  nearly  all,  if  not  all,  those  distinctions  which  cause  the 
eruptive  rocks  to  be  divided  into  older  and  younger,  or  into  pre-Tertiary,  and 
Tertiary  and  recent.  It  is,  then,  claimed  that  geological  age  has  no  bearing 
on  classification  beyond  this :  that  the  older  rocks  of  the  same  type  or 
species  are,  the  greater  is  their  alteration  under  like  conditions ;  and  that 
the  greater  number  of  the  so-called  rock -species  of  pre-Tertiary  age  are  the 
altered  forms  of  rocks  which  were  once  identical  with  Tertiary  and  modern 
rocks.  The  original  or  eruptive  rocks  of  the  universe  appear  to  form  a  con- 
tinuous series,  from  the  most  basic  to  the  most  acidic ;  but  for  convenience 
they  are  to  be  divided  into  definite  species,  types,  or  groups,  which  on  the 
boundaries  will  naturally  fade  into  one  another.  The  preponderance  of 
characters,  and  not  the  presence  or  .absence  of  any  one  mineral  ought  to 
decide  the  place  of  any  rock  in  the  system,  and  the  original  characters  ought 
to  hold  priority  in  classification  over  any  that  are  of  a  secondary  nature 
(alteration,  etc.). 

The  natural  classification,  in  its  broader  applications,  can  be  employed  in 
the  field  as  well  as  in  the  laboratory ;  for,  as  a  rule,  all  the  characters  of 
rocks  are  so  related  to  one  another  that  from  one  the  others  can  be  inferred 
with  a  fair  degree  of  accuracy. 


56  CLASSIFICATION   IN   LITHOLOGY.  —  GENERAL   CONCLUSIONS. 

When  complete  (bausch)  analyses  are  made  of  typical  rocks,  rock-species 
are  believed  to  have  in  their  broader  features  certain  limits  of  chemical 
composition  outside  of  which  the  normal  forms  rarely  go,  and  inside  of 
which  the  normal  forms  of  other  species  rarely  come ;  but  the  mineralogical 
composition  is  more  or  less  unstable  and  variable,  depending  upon  alteration 
and  other  conditions  to  which  the  rock  has  been  subjected.  It  is  thought 
that  the  chemical  relation  of  rock  species  would  be  much  better  shown  if 
the  percentages  were  expressed  in  terms  of  the  elements,  instead  of  in  their 
compounds  —  as  Nordenskiold  has  suggested  for  the  meteorites. 

All  rocks,  except  meteoric  and  recent  volcanic  ones  appear  to  be  more  or 
less  altered ;  and  it  is  evidently  from  these  altered  rocks  that  the  classifica- 
tions and  principles  of  classification  have  been  chiefly  derived  in  Europe,  on 
the  supposition  that  as  these  rocks  are  now  found  to  be,  so  they  always  were, 
and  always  will  be. 

Fragmental  or  derived  rocks  ought  to  be  classed,  ,so  far  as  it  is  possible, 
under. the  rocks  from  which  they  were  derived;  the  object  of  the  classifica- 
tion both  of  these  and  the  massive  rocks  being  to  show  their  relations  and 
derivation  so  far  as  practicable. 

The  relation  of  one  rock  to  its  fellows  in  the  field  is  the  principal  crite- 
rion for  determining  its  origin  —  particularly  in  the  case  of  altered  rocks. 

Taking  the  consolidation  of  any  rock  as  the  datum  point,  the  minerals 
and  rock  fragments  are  found  to  be  naturally  divided  into  three  distinct 
classes  of  different  origin  :  — 

1.  Minerals  and  fragments  of  prior  origin. 

(a)  Those  characteristic  of  the  rock  species. 
(5)  Those  that  are  accidental. 

2.  The  products  of  the  consolidation. 

3.  The  products  of  alteration  and  infiltration. 

All  may  exist  together  in  a  rock,  or  all  except  those  of  one  class  may  be 
wanting ;  and  far  more  depends,  in  lithology,  on  being  able  to  determine  the 
origin  and  relations  of  these  different  classes  of  minerals  than  on  ability 
to  name  the  mineral  species  correctly.  Minerals  of  the  third  class  are 
apparently  formed  through  the  agency  of  percolating  Avaters,  which  may 
be  hot  or  cold. 

The  alterations  appear  in  general  to  take  place  slowly ;  while  rapid  alter- 
ations, such  as  would  be  produced  by  hot,  intensely  active  waters,  generally, 
if  not  always,  seem  to  bear  distinctive  marks. 


CLASSIFICATION   IX   LITHOLOGY.  —  GENERAL  CONCLUSIONS.  57 

In  practically  employing  the  principles  given  before,  all  kinds  of  rocks, 
whether  from  the  earth'  or  heavens,  are  naturally  to  be  described  and 
arranged,  but  only  a  limited  portion  of  this  work  can  be  done  here.  In 
the  execution  of  this  the  most  basic  rocks  known  will  be  taken,  and  the 
gradations  between  the  different  states  traced  as  far  as  practicable. 

The  order  will  be  to  pass  from  the  glassy  to  the  most  perfectly  crystalline 
state ;  from  the  least  altered  towards  the  most  altered ;  from  the  most  basic 
towards  the  most  acidic ;  from  the  non-fragmental  to  the  fragmental  or 
clastic.  In  the  case  of  the  fragmental  rocks,  it  is  intended  to  proceed  from 
the  least  altered  to  the  most  altered ;  that  is,  from  those  little  consolidated 
towards  those  most  indurated ;  from  the  unaltered  towards  those  most  highly 
metamorphosed.  In  the  wide  range  of  roeks  studied,  it  has  been  found  as  a 
rule  that  the  macroscopic  and  microscopic  characters  could  generally  be 
inferred  one  from  the  other ;  and  that,  likewise,  from  these  the  chemical  com- 
position could  be  declared,  within  certain  general  limits.  Indeed,  by  the 
method  of  classification  pursued  here,  a  bit  of  unaltered  groundmass,  not  pure 
glass,  sufficient  to  fill  the  field  of  a  No.  7  or  9  Hartnack  objective,  is  enough 
to  enable  one  to  tell  the  species  to  which  the  rock  belongs,  and  to  give  some 
general  idea  of  its  composition,  both  chemically  and  mineralogically. 

In  applying  the  earlier  given  principles  of  nomenclature  and  classifica- 
tion, the  following  method  has  been  practically  adopted  here :  All  the 
rocks,  from  one  end  of  the  series  to  the  other,  are  divided  into  species  or 
groups ;  and  each  of  these  species  possesses  the  general  characters  that  have 
usually  found  voice  in  the  generally  established  'nomenclature.  Since  the 
most  typical  forms  are  those  of  the  modern  eruptive  rocks,  their  names, 
when  practicable,  have  been  selected,  and  in  them  the  limits  of  the  species  is 
made  as  nearly  as  possible  coincident  with  those  made  by  the  leading  lithol- 
ogists.  Of  course  they  are  not  absolutely  identical,  for  natural  boundaries 
do  not  correspond  entirely  with  the  artificial  fences  made  by  man.  Under 
these  specific  or  group  names  —  such  as  basalt,  andesite,  trachyte,  and 
rhyolite  —  are  placed,  as  varieties,  the  altered,  as  well  as  older  (pre-Ter- 
tiary)  forms;  which  it  is  thought  were  once  identical  with  the  unaltered 
or  modern  forms.  The  variety  names  are  also  used  as  nearly  as  possible  in 
their  more  general  applications ;  but  it  is  often  found  that  the  artificial  boun- 
daries of  these  varieties  (regarded  by  other  lithologists  as  distinct  species) 
carry  them  into  two  or  more  of  the  species,  as  that  term  is  used  here ;  e.  y., 
melaphyr  is,  as  a  rule,  a  name  given  to  the  fine.-grained  older  and  altered 


58  CLASSIFICATION    IN    LITHOLOGY.  —  GENERAL  CONCLUSIONS. 

rocks  belonging  to  the  species  basalt,  but  in  some  cases  the  older  forms  of 
andesite  have  been  described  as  melaphyrs.  So,  too,  the  term  diabase 
includes  under  it,  in  the  common  artificial  nomenclature,  both  old  basaltic 
and  andesitic  rocks  —  a  fact  which  has  been  imperfectly  recognized  in  the 
division  of  the  diabases  into  diabase  and  olivine-diabase.  In  this  work 
the  term  melaphyr  and  diabase  will  be  confined  to  the  rocks  belonging 
under  basalt,  which  possess  the  general  characters  of  the  ordinary  melaphyr 
and  diabase  type.  In  the  case  of  some  names  —  like  diorite,  which  has  been 
commonly  used  for  a  wide  range  of  old  and  more  highly  altered  rocks  than 
those  to  which  the  names  melaphyr  and  diabase  have  been  iisually  given  —  a 
greater  difficulty  occurs  in  practical  use.  Such  names  are  placed  as  sub- 
varietal  names,  after  the  names  -of  the  variety  or  species  to  which  they 
belong,  in  order  to  indicate  the  line  of  derivation. 

Many  terms  have  been  given  in  the  past  to  rocks,  indicating  some  special 
stage  in  their  alteration,  which  are  not  of  sufficient  importance  to  be  used  as 
a  variety  or  sub-variety  form.  These  terms  are  sometimes  inclosed  in  a 
parenthesis  and  placed  after  the  specific  or  variety  name.  It  is  necessary  to 
place  those  rocks,  whose  derivation  is  nojt  clear,  as  nearly  as  possible  in  their 
apparently  proper  situation,  leaving  it  to  the  future  to  correct  and  amend 
the  classification. 

The  fragrnental  rocks  are  placed,  so  far  as  possible,  under  the  rocks  from 
which  they  are  derived  ;  but  those  whose  derivation  is  unknown,  it  is  in- 
tended to  describe  and  classify  according  to  the  common  method  of  nomen- 
clature, as  the  best  now  practicable. 

The  recent  or  unaltered  fragmental  rocks  will  be  placed  as  tufas  under 
their  proper  species,  while  the  older  and  altered  forms  will  be  classed  as 
porodites,*  under  their  respective  species  and  varieties. 

The  object  is  to  show  the  natural  relations  of  the  rocks  so  far  as  possible, 
and  at  the  same  time  to  interfere  but  little  with  the  customary  use  of  litho- 
logical  names. 

As  illustrations  of  my  meaning,  the  following  examples  may  be  given, 
the  label  of  a  melaphyr  would  be  written  as  follows:  Basalt,  Melaphyr  — 
the  following  term  being  always  subordinate  to  the  preceding  one  in  this 
order:  species,  variety,  sub-variety,  etc.,  while  any  one  of  the  names  can 
be  used  in  speaking  of  the  rock. 

If  a  rock  to  which  the  name  diorite  would  be  applied  in  ordinary  nomen- 

*  Bull.  Mus.  Comp.  Zoo!.,  1879,  v.  2SO. 


CLASSIFICATION  IN  LITHOLOGY.  — GENERAL  CONCLUSIONS.  59 

clature  is  found,  from  its  structure  and  composition,  to  come  under  either 
melaphyr  or  diabase,  its  label  would  be  written  as  follows,  according  as  it 
was  one  or  the  other :  — 

Basalt,  Melaphyr,  Diorite. 
Basalt,  Diabase,  Diorite. 

But  if  this  diorite  belonged  apparently  to  the  basaltic  species,  but  could 
not  be  referred  to  either  the  melaphyr  or  diabase  variety,  its  label  would  be 
thus :  Basalt,  Diorite. 

When  the  names  are  trivial,  or  when  they  are  not  properly  variety  or 
sub-variety  names  of  the  species  under  which  the  specimen  is  placed,  the 
label  is  written  as  follows :  Basalt,  Diabase  (Calc-Diabase).  For  the  frag- 
mental  forms  it  is  written,  Basalt,  Tufa;  or  Basalt,  Porodite ;  or  Basalt,  Dia- 
base, Porodite  —  as  the  case  may  be. 

The  variety  and  sub-variety  names  are  not  here  considered  essential,  but 
are  employed  out  of  deference  to  the  common  custom.  However,  in  order 
to  make  the  work  symmetrical,  such  names,  and  even  new  ones,  have  been 
introduced,  where  it  seemed  necessary  ;  but  all  can  be  dropped  or  continued, 
and  expanded  as  the  advance  of  the  science  may  require. 

The  special  nomenclature  and  its  applications  will  be  given  in  the  descrip- 
tive portion  of  the  work,  with  the  account  of  the  specimens,  and  to  that  the 
reader  is  referred.  If,  in  course  of  time,  a  system  of  nomenclature  like 
that  employed  in  botany  and  zoology,  should  be  desired,  the  system  em- 
ployed here  would  readily  furnish  it,  by  dropping  the  commas  between 
the  specific  name  and  its  variety  and  sub-variety,  with  the  Latinization  of 
these  names.  The  names  would  then  be  in  their  proper  order,  and  afford 
us  both  binomial  and  trinomial  names,  as  the  case  might  be. 


CHAPTER    II. 

THE  SIDEROLITES  AND  PALLASITES. 

SECTION  I.  —  Siderolite. 

IN  this,  the  first  or  most  basic,  species  or  group,  the  rock  is  composed 
chiefly  of  iron  —  either  native  or  in  its  secondary  states,  as  magnetite, 
hematite,  menaccanite,  etc.  —  and  with  or  without  nickel,  schreibersite, 
pyrrhotite,  graphite,  etc. 

It  includes  all  those  masses  of  iron  and  iron  ore  that  have  fallen  as 
meteorites,  or  which  formed  an  original,  not  secondary,  portion  of  the  earth, 
or  are  of  eruptive  origin,  or  directly  derived,  as  fragmental  deposits,  from 
any  of  these.  No  veins  or  chemical  deposits  of  iron  ore  are  intended  to  be 
included  in  this  species. 

The  characters  of  the  supposed  meteoric  siderolites  have  been  so  fully 
described  in  numerous  papers  and  treatises  on  the  subject,  that  it  is  not 
necessary  to  describe  them  here  in  any  detail.  A  few  specimens  only  will 
be  spoken  of  below,  that  the  writer  has  seen,  which  will  give  a  few  of  the 
characteristics. 

In  such  meteoric  siderolites  as  that  from  SHINGLE  SPRINGS,  ELDORADO 
Co.,  CALIFORNIA,  the  iron  is  in  a  nearly  homogeneous  mass,  since  only  two 
small  masses  of  pyrites  have  been  reported  to  have  been  found  in  it. 
The  etched  surface  of  a  specimen  in  Professor  Whitney's  collection  shows 
an  obscure  granular  structure,  which  under  the  lens  is  seen  to  be  formed 
by  some  brilliant  points,  and  small  elongated  ridges  of  like  bright  metallic 
lustre,  rising  above  the  dull  gray  surface  left  by  the  acid. 

Professor  B.  Silliman  states  of  a  specimen  in  his  possession  that  the 
etched  surface  showed  under  a  lens  "  a  reticulated  structure  with  numerous 
brilliant  points  and  v-shaped  lines."  * 

The  meteoric  siderolite  from  STANTON,  AUGUSTA  Co.,  VIRGINIA,  is  a  very 

*  Amer.  Jour.  Sci.,  1873  (3),  vi.  18-22. 


SIDEROLITE  61 

compact  mass  of  iron,  showing  only  a  few  small  nodules  of  pyrrhotite.  A 
general  description,  with  figures  showing  the  structure  of  its  etched  surface, 
has  been  given  by  Professor  J.  W.  Mallet.* 

A  specimen  of  the  COAIIUILA  (Mexico)  siderolite  in  the  Harvard  Col- 
lege Mineral  Cabinet  shows  a  compact  mass  of  iron,  with  irregularly  distrib- 
uted elongated  cells  filled  with  pyrrhotite.  The  chief  portion  of  the  iron 
seems  to  be  free  from  these  irregular  masses  of  pyrrhotite,  but  some  parts 
are  quite  filled  with  them. 

The  TEXAS  (Giuus)  siderolite  in  the  same  collection  shows  a  compact 
metallic  mass,  holding  a  few  rounded  and  irregular  cells  containing  pyrrho- 
tite. This  rock  has  been  described  by  Professors  Silliman  and  Hunt,  who 
also  give  a  plate  representing  the  Widmannstattian  figures.! 

The  specimen  of  the  BUTLER  (BATES  COUNTY,  MISSOURI)  siderolite  in  the 
Harvard  College  Cabinet  is  very  compact,  but  contains  a  few  elliptical  and 
irregular  cells  filled  with  pyrrhotite  (troilite)  surrounded  by  rings.  These 
rings  connect  with  the  raised  bands  shown  by  etching.  Some  of  the  bands, 
indeed,  appear  as  offshoots  from  the  rings.  In  this  specimen  the  etching  has 
not  brought  out  the  Widmannstattian  figures  very  clearly,  yet  the  above 
relations  can  be  distinguished.  A  brief  description  of  this  siderolite  was 
given  by  Professor  J.  Lawrence  Smith,  with  analysis  of  the  iron  alone.  The 
nodules  of  troilite,  according  to  him,  were  numerous,  but  free  from  any 
schreibersite.  In  his  specimen  the  Widmannstattian  figures  were  readily 
developed  and  found  to  be  large  and  regular,  t 

Some  siderolites  like  that  from  TOLUCA,  MEXICO,  in  the  Harvard  College 
Cabinet  are  composed  of  a  very  coarse  sponge-like  mass  of  iron,  holding 
detached  irregular  masses  of  pyrrhotite,  etc.  In  this  the  distance  across  the 
iron  from  one  cell  wall  to  another  cell  wall  is  greater  than  the  diameter 
of  the  cells  themselves. 

The  general  structure  of  the  meteoric  form  may  then  be  said  to  be  a  mass 
of  iron,  or  of  iron  inclosing  more  or  less  irregular  and  nodular  masses  of 
pyrrhotite,  schreibersite,  graphite,  etc. 

Associated  with  the  meteoric  iron,  in  intimate  union  with  it  or  in  com- 
binations of  their  own,  occur  nickel,  cobalt,  magnesium,  aluminum,  calcium, 
silicon,  chromium,  phosphorus,  copper,  carbon,  arsenic,  sulphur,  tin,  mangan- 
ese, potassium,  sodium,  chlorine,  oxygen,  beryllium,  etc. 

»  Amer.  Jour.  Sci.,  1871  (3),  ii.  10-15,  1878  ;  xv.  337,  338. 
f  Am.  Jour.  Sci.,  18 Hi  (2),  ii.  H70-:576. 
j  Am.  Jour.  Sci.,1877  (3).  xiii.  213. 


62  THE  SIDEEOLITES   AND   PALLASITES. 

In  a  large  number  of  the  siderolites,  etching  develops  in  the  iron  those 
structural  planes,  well  known  as  the  Widmannstattiau  figures,  parallel  to 
the  planes  of  the  isometric  octahedron  and  cube.  This  structure  is  parallel- 
ized by  the  cleavage  observed  in  magnetite,  and  by  the  observed  structure 
produced  in  titaniferous  iron  during  the  process  of  its  alteration  to  "  leuco- 
xene."  Indeed,  many  of  the  altered  titaniferous  irons  show  a  structure  closely 
resembling  some  of  the  Widmannstattian  figures.  These  latter  figures  can 
be  taken  no  longer  as  proofs  of  the  meteoric  origin  of  any  iron,  since  they 
have  been  developed  in  the  terrestrial  iron  of  the  Greenland  basalts.  The 
Widmannstattian  figures  are  so  well  known  that  it  is  unnecessary  to  repro- 
duce them  in  the  plates  of  this  work,  especially  since  good  examples  can  be 
found  in  the  following  papers  and  works :  — 

Schreibers's  Beitrage  zur  Geschichte  und  Kenntniss  meteorischer  Stein- 
und  Metall-Massen,  Wien,  1820 ;  Clark  on  Metallic  Meteorites,  Cottingen, 
1853;  Biichner,  Bericht  Ober.  Gesell.  Giessen,  I860,  xiii.  99-115;  Haidinger, 
Sitz.  Wien.  Akad.,  1855,  xv.  354-360 ;  1862,  xlv.  (2),  65-74 ;  xlvi.  (2),  286- 
297;  1863,  xlviii.  (2),  301-308;  Amer.  Jour.  Sci.,  1846,  (2),  ii.  370-376, 
1853,  xv.  363 ;  Brezina,  Denks.  Wien.  Akad.,  1881,  xliii.  13-16 ;  1884,  xliv. 
121-158;  Tschermak,  Sitz.  Wien.  Akad.,  1874,  Ixx.  (1).  443-458;  Denks. 
Wien.  Akad.,  1872,  xxxi.  187-195;  Gustav  Kose,  Abh.  Berlin.  Akad.,  1863, 
pp.  23-161,  etc. 

It  is  possible  that  could  chemical  analyses  be  made  that  would  yield  the 
constitution  of  the  siderolite  masses  as  a  whole,  and  thus  enable  their  min- 
eralogical  and  chemical  constitution  to  be  coordinated  Avith  their  structure, 
that  the  species  siderolite  might  be  separated  into  several  distinct,  natural, 
and  well  marked  species.  The  most  probable  divisions  would  be  into  those 
composed  of  metallic  iron,  and  those  formed  from  metallic  iron  and  pyrrho- 
tite.  The  first  might  possibly  be  separated  into  those  bearing  much  nickel 
and  those  of  nearly  pure  iron.  Of  course,  no  such  subdivision  of  siderolite 
should  be  attempted  unless  the  composition  and  structure  both  pointed 
towards  the  separation.  This  would  require  the  study  of  a  large  number  of 
siderolites,  an  opportunity  for  which  the  writer  has  not,  even  if  satisfactory 
chemical  analyses  existed. 

A  list  of  chemical  analyses  has  indeed  been  collected  and  will  be 
appended ;  but  it  is  far  from  being  what  could  be  desired,  since  it  is  the 
custom  of  chemists  to  select  the  purest  portion  of  the  iron  for  analysis.  In 
fact  but  few  analyses  exist  of  siderolites  that  can  be  regarded  as  complete 


SIDEROLITE.  C3 

when  the  mass  contains  other  minerals  than  the  iron  itself.  Each  separate 
mineral  is  analyzed,  but  the  general  average  of  the  whole  mass  is  un- 
known. Indeed,  in  many  cases  it  may  be  difficult  if  not  impossible, 
owing  to  its  structure,  to  obtain  the  composition  of  the  whole,  except 
approximately. 

Since  the  same  mineral  has  nearly  the  same  constitution,  whatever  may 
be  its  associations,  the  native  iron  would  be  expected  to  yield  the  same 
constituents  whether  in  a  large  mass  alone  or  in  minute  grains  associated 
with  other  minerals.  Consequently,  the  analyses  of  meteoric  irons  as  now 
carried  on  afford  but  little  clue  to  their  structure,  for  a  pallasite  yields  the 
same  result  as  a  siderolite,  so  far  as  the  usual  published  analyses  show. 

The  specific  gravity  of  the  siderolites  varies  considerably,  but  by  far  the 
greater  portion  lie  between  7.50  and  7.90.  The  highest  number  is  8.31,  and 
the  lowest  5.75,  but  the  average  may  be  considered  to  be  about  7-70.  The 
analyses  of  the  siderolites  have  been  arranged  according  to  their  percentage 
of  metallic  iron,  for  in  that  way  their  relations  could  be  best  shown  ;  but 
where  there  are  seveml  analyses  of  the  same  rock,  all  are  placed  together 
without  regard  to  the  percentage  of  the  iron,  except  in  the  case  of  the  first 
one  in  the  given  series.  The  predominating  percentages  lie  between  87.00 
and  97.00,  the  average  being  about  91.00.  The  highest  percentage  of  iron 
is  99.81  and  the  lowest  37.00;  but  only  seven  analyses  show  a  lower  per- 
centage than  80.00. 

The  percentage  of  nickel,  as  a  rule,  in  the  meteoric  siderolites  varies 
inversely  with  the  iron ;  and  if  it  is  taken  in  connection  with  its  associated 
cobalt  and  the  iron  —  whether  free,  or  united  with  sulphur  or  phosphorus 
-  it  is  found  that  with  but  few  exceptions  the  three  elements  make  over 
99  per  cent  of  the  mass.  The  nickel  varies  in  amount  from  none,  in  seven 
analyses,  and  to  .10  and  .20  per  cent,  up  to  12,  14,  and  15  per  cent.  In 
three  extreme  cases  it  was  found  to  be  24.708,  36.00,  and  59.69  per  cent. 
The  percentage  of  nickel  in  the  Greenland  siderolites  is  low.  One  serious 
difficulty  in  estimating  the  relative  proportions  of  the  iron,  nickel,  and  cobalt 
is  the  apparent  unreliability  of  many  of  the  analyses  —  a  difference  of  about 
four  per  cent  existing  in  the  nickel  as  determined  from  the  same  siderolite  ; 
and  in  an  extreme  case  one  chemist  obtained  14.70  per  cent  of  nickel,  and 
another  none.  As  a  rule,  cobalt  is  in  amount  less  than  one  per  cent,  but  in 
a  few  cases  reaches  between  two  and  three  per  cent,  and  in  one  instance  is 
between  three  and  four  per  cent.  Probably  it  is  always  present  with  nickel, 


64  THE   SIDEROLITES   AND   PALLASITES. 

but  is  not  found,  owing  to  imperfect  methods,  which  cause  the  cobalt  to  be 
wanting  in  a  large  number  of  analyses. 

As  a  rule,  the  other  elements  found  in  siderolites  are  in  very  small 
amounts,  if  not  entirely  wanting;  although  in  one  case  15.359  per  cent  of 
sulphur  was  reported.  The  analyses  indicate  that  phosphorus,  sulphur,  cop- 
per, and  possibly  carbon  (graphite)  are  always  present  in  the  siderolites  and 
can  be  found  when  searched  for  with  sufficient  care.  The  greater  the  skill, 
the  greater  the  number  of  elements  found,  and  both  appear  to  be  roughly 
and  inversely  proportionate  to  the  amount  of  iron  reported. 

Of  course  it  is  to  be  remembered  that  these  analyses  were  made  from 
picked  portions,  and  they  do  not  give  a  fair  average  of  the  siderolite  masses 
as  a  whole. 

None  of  the  analyses  of  the  oxidized  siderolites  have  been  given  in  the 
tables ;  for  while  they  are  quite  abundant,  most  of  them  are  too  imperfect  to 
serve  any  useful  purpose  for  comparison,  since  they  have  been  made  for 
commercial  purposes  only.  In  the  case  of  these  terrestrial  siderolites,  it  is 
desirable  to  have  them  carefully  selected,  typical,  and  of  known  origin,  and 
then  most  carefully  tested  for  the  rare  elements. 

It  is  to  be  presumed  that  the  native  iron,  coming  to  the  surface  of  the 
earth  from  below,  would  as  a  rule  either  be  oxidized  at  that  time  or  during 
its  subsequent  existence ;  hence  in  but  few  cases  is  it  naturally  to  be 
expected  that  metallic  iron  would  occur  to  any  especial  extent  on  that 
surface. 

In  its  oxidized  forms,  and  in  association  with  a  rock  belonging  at  the 
other  extreme  of  the  lithological  scale,  siderolite  occurs  on  the  southern 
shore  of  Lake  Superior. 

Since  the  author  has  quite  fully  discussed  the  evidence  that  causes  him 
to  believe  in  the  eruptive  origin  of  most  of  the  magnetite  and  hematite  of 
the  Marquette  district  of  Lake  Superior,  it  is  unnecessary  to  discuss  the  sub- 
ject farther  here.  The  other  chief  works  relating  to  these  ores  are  the 
Geological  Reports  of  Messrs.  Foster  and  Whitney,  and  T.  B.  Brooks.  A 
general  discussion  of  the  various  theories  and  of  the  evidence,  as  well  as  a 
list  of  the  works  relating  thereto,  has  been  given  by  the  writer  in  the  papers 
referred  to  below.* 

From  the  various  accounts  given  of  the  occurrence  of  iron  ores  in  this 
country  and  elsewhere,  it  is  probable  that  many  other  eruptive  iron  ore 

*  Bull.  Mus.  Comp.  Zool.,  1880,  vii.  1-157,  6  plates;  Proc.  Bost.  Soc.  Nat.  His.,  1880,  xx.  470-479. 


SIDEROLITE.  65 

masses  exist  which  properly  should  come  under  the  species  siderolite.  How- 
ever, it  is  .an  open  question,  and  it  will  probably  remain  so  until  these 
deposits  can  be  studied  with  the  view  of  ascertaining  the  facts  bearing  upon 
their  origin,  unbiassed  by  any  preconceived  theories  of  that  origin. 

The  native  iron  found  in  Greenland  may  properly  be  mentioned  here, 
as  it  is  possibly  a  portion  of  the  earth's  metallic  core  brought  to  the  surface 
by  the  associated  basalt.  The  iron  is  in  large  masses  associated  with  basaltic 
rocks,  as  well  as  in  fine  grains  intimately  mixed  with  the  basalt  itself  and 
taking  the  place  of  the  ordinary  iron  ores  that  generally  occur  in  that  rock. 
It  occurs  with  schreibersite,  pyrrhotite  (troilite)  graphite,  and  magnetite,  the 
same  as  native  iron  commonly  does  in  meteorites.  On  etching,  the  Wid- 
mannstHttian  figures  are  produced,  and  thus  this  iron  shows  characters  that 
have  usually  been  regarded  as  exclusively  belonging  to  meteoric  irons. 
These  figures  are  produced  even  on  the  little  grains,  six  to  seven  millimeters 
in  diameter,  occurring  in  the  basalt.  Whether  the  Greenland  iron  came  from 
the  interior  of  the  earth  as  metallic  iron,  as  the  writer  thinks  most  probable, 
or  was  produced  by  the  reducing  agency  of  carbon  on  some  ores  of  iron,  as 
maintained  by  Steenstrup  and  Smith,  there  appears  at  present  no  doubt  that 
it  is  of  terrestrial  origin. 

Of  the  large  number  of  metallic  siderolites  that  have  been  described, 
but  very  few  are  known  to  be  of  meteoric  origin,  only  some  seven  having 
been  seen  to  fall ;  while  the  localities  in  which  so  many  occur  —  in  moun- 
tainous districts,  and  in  regions  in  which  eruptive  action  has  been  intense 
—  are  such  that  in  regard  to  many,  doubt  must  exist  regarding  their  cos- 
mic origin.*  Indeed,  if  they  are  truly  of  meteoric  origin,  there  is  a  most 
remarkable  concurrence  of  localities  in  which  telluric  iron  would  naturally 
occur,  if  at  all,  and  the  places  in  which  iron  in  relatively  large  amounts 
has  fallen. 

It  would  seem  that  chemical  analysis  should  not  be  made  the  sole  judge 
regarding  the  origin  of  these  numerous  supposed  meteorites.  It  would 
appear  to  be  necessary  that  a  petrographical  or  geological  study  of  the 
localities  in  which  these  bodies  are  found  should  be  made ;  and  they  ought 
to  be  regarded  as  doubtful  meteorites,  unless  the  circumstances  of  their 
occurrence  preclude  their  terrestrial  origin.  That  no  attempt  has  been 
made,  as  a  rule,  to  ascertain  the  origin  of  these  masses  of  iron,  beyond 
chemical  tests,  will  be  seen  from  the  following :  — 

*  The  conditions  under  which  the  Baliia  siderolite  was  found  renders  it  not  improbable  that  this  is  of 
similar  origin  with  the  Ovifak  iron.     See  A.  F.  Mornay,  Phil.  Trans.,  181G,  pp.  270-285. 

9 


66  THE   SIDEEOLITES   AND   PALLASITES. 

"  Chemistry  has  entirely  dissipated  all  doubts  in  the  matter,  and  now  an  examination 
in  the  laboratory  of  the  chemist  is  entitled  to  more  credit  than  evidence  from  any  other 
source  in  pronouncing  on  the  meteoric  origin  of  a  body.  No  question  need  be  asked  as 
to  whether  it  was  seen  to  fall,  or  whether  this  or  that  rock  or  mineral  exists  in  the  neigh- 
borhood where  it  may  have  been  collected.  The  reagents  of  the  chemist  alone  are  uner- 
ring indications  that  suffice  to  set  aside  all  cavilling  in  the  matter."  * 

The  above  statement  rests  upon  the  assumption  that  no  terrestrial  ma- 
terial under  any  circumstances  can  possess  the  same  chemical  characters 
that  meteorites  do !  This  basis  is  the  one  upon  which  most  investigations 
of  supposed  meteoric  irons  now  proceed,  and  have  proceeded  for  many 
years ;  t  a  basis  that  has  never  been  carefully  investigated,  and  which 
many  would  probably  repudiate  since  the  Ovifak  discovery.  Would  it  not 
be  well  if  a  more  thorough  study  could  be  made  of  the  conditions  under 
which  so  many  siderolites  have  been  found  in  the  southwestern  portion  of 
the  United  States,  Mexico,  and  South  America  ? 

The  origin  of  the  meteoric  masses  of  iron  has  been  a  question  upon  which 
speculation  has  been  rife.  It  has  been  suggested  that  they  and  the  other 
meteorites  were  formed  in  our  own  atmosphere ;  that  they  were  thrown 
from  terrestrial  or  lunar  volcanoes ;  or  thrown  from  the  sun ;  the  remains 
of  a  shattered  planet ;  some  of  the  spare  material  left  over  when  the  solar 
system  was  made.  etc.  It  concerns  this  work  principally  to  examine  the 
views  of  those  who  have  made  microscopical  studies  of  siderolites,  and  not 
to  discuss  the  general  theories  of  others ;  however,  it  will  be  necessary  later 
to  point  out  the  probable  origin  of  meteorites  as  deduced  from  their  micro- 
scopic characters.  One  of  the  most  prominent  of  the  students  of  meteor- 
ites is  Professor  Gustav  Tschermak,  who  stated  in  1875  that 

"  the  greater  number  of  meteoric  irons  exhibit  a  structure  which  indicates  that  each  has 
formed  part  of  a  large  mass  possessing  similar  crystalline  characters.  The  formation  of 
large  masses  so  constituted  presupposes,  as  Haidinger  has  pointed  out,  long  intervals  of 
time  for  tranquil  crystallization  at  a  uniform  temperature,  and  these  conditions  could 
only  prevail  on  one  of  the  larger  cosmical  masses."  J 

A  microscopic  examination  of  the  figures  observed  upon  the  etched  sur- 
face of  meteoric  and  artificial  irons,  led  Mr.  Sorby  to  the  following  con- 
clusions :  — 

"  These  facts  clearly  indicate  that  the  Widmanstatt's  figuring  is  the  result  of  such  a 
complete  separation  of  the  constituents,  and  perfect  crystallization,  as  can  occur  only  when 

*  J.  Lawrence  Smith's  Mineralogy  ami  Chemistry,  Louisville,  Ky.,  1873,  p.  290. 
f  Newcomb's  Astronomy,  1st  ed.,  1873,  p.  386 ;  4th  ed.  1882,  p.  397- 

J  Phil.  Mag.,  1876  (5)  i.  499  ;  Sit/..  Wien.  Akad.,  1875,  Ixxi.  (;>),  661-6/3.  See  also  J.  Lawrence 
Smith's  Memoir  on  Meteorites,  Aim.  Rep.  Smith.  lust.,  1S55,  p.  158. 


SIDEROLITE.  67 

the  process  takes  place  slowly  and  gradually.  They  appear  to  me  to  show  that  meteoric 
iron  was  kept  for  a  long  time  at  a  heat  just  below  the  point  of  fusion,  and  that  we 
should  be  by  no  means  justified  in  concluding  that  it  was  not  previously  melted.  Similar 
principle's  are  applicable,  in  the  case  of  the  iron  masses  found  in  Disco;  and  it  by  no 
means  follows  that  they  are  meteoric,  because  they  show  the  Widmanstatt's  figuring. 
]>il'l'cTciiee  in  the  rate  of  cooling  would  serve  very  well  to  explain  the  difference  in  the 
structure  of  some  meteoric  iron  [s],  which  do  not  differ  in  chemical  composition  ;  but  as 
far  as  the  general  structure  is  concerned,  I  think  that  we  are  quite  at  liberty  to  conclude 
that  all  may  have  been  melted,  if  this  will  better  explain  other  phenomena."  * 

It  would  appear  that  these  observers  advocate  the  view  that  the  sidero- 
litc-s  must  have  been  subjected  to  a  long  and  slow  cooling  upon  some  body 
of  sufficient  size  to  yield  the  required  conditions ;  but  since  the  same  struc- 
ture can  be  developed  in  the  iron  of  the  stony  meteorites,  which  show  evi- 
dence of  rapid  cooling,  the  writer  is  compelled  reluctantly  to  differ  from 
these  eminent  observers,  and  to  hold  that  while  the  Widmannstiittian  figures 
may  have  originated  as  they  have  claimed,  they  may  occur  as  readily  in  a 
small  mass,  cooling  at  a  comparatively  rapid  rate,  and  therefore  their  origin 
is  to  be  explained  in  some  other  way.  In  other  words,  as  yet,  there  is  no 
evidence  that  Sorby's  and  Tschermak's  views  are  correct. 

It  is  probable  that  but  few  will  claim  that  the  siderolites  of  meteoric 
origin  were  formed  by  organic  agencies.  If  they  were  not,  it  follows  that 
the  graphite  contained  in  them  could  not  have  been  so  produced.  This  has 
a  very  direct  and  obvious  bearing  on  the  question  whether  the  graphite  in 
Azoic  and  other  rocks  need  have  been  derived  from  animal  or  plant  remains, 
and  it  negatives  the  supposition.! 

To  make  graphite  the  evidence  of  life  is  the  same  kind  of  argument  as  it 
is  to  claim  that  no  oxides  of  iron  and  no  carbonate  of  lime  could  be  formed 
without  the  intervention  of  life.  One  we  knew  to  be  oftentimes  of  volcanic 
origin,  and  the  other  to  be  frequently  the  product  of  the  decomposition  of 
rocks.  It  is  too  much  to  assume,  because  minerals  are  known  to  form  in 
certain  conditions,  or  can  be  formed  in  certain  ways,  that  they  must  always 
be  made  in  that  way.  None  of  the  meteorites  now  known  appear  to  indi- 
cate that  they  came  from  a  region  where  life  could  exist  as  we  know  it; 
hence,  it  does  not  seem  proper  to  claim  that  life  must  have  intervened  in 
their  formation  merely  because  a  mineral  is  found  in  them  that  is  ordinarily 
supposed  to  be  of  organic  origin. 

«  Nature,  1877,  xv.  498. 

t  J.  Lawn-nee  Smith,  Mineralogy  and  Chemistry,  1873,  pp.  284-310;  Am.  Jour.  Sci,187fi  (3),  xi.  388- 
395,  «3-H2  ;  Walter  Flight,  Pop.  Sci.  Rev.,  1877",  xvL  390-401. 


68  THE  SIDEROLITES   AND   PALLASITES. 

The  term  siderolite,  or  rather  aero-siderolite  was  proposed  by  Professor 
N.  Story  Maskelyne,  for  the  meteorites  to  which  Gustav  Rose  had  previously 
given  the  name  pallasite.  Rose  afterwards  divided  his  pallasites,  retaining 
the  original  term  for  all,  except  two  specimens,  which  he  classed  as  mesosi- 
derites.  These  Maskelyne  united  again,  but  instead  of  using  the  term  pal- 
lasite for  all,  proposed  the  name  above  given.  The  name  pallasite  belongs 
by  prior  right  to  these  forms,  while  siderolite  does  not ;  therefore,  I  trust 
Prof.  Maskelyne  will  permit  the  transference  of  his  term  siderolite,  as  his 
own,  from  the  pallasites  to  the  forms  that  I  have  herein  classed  under  the 
former  name.  It  is  impracticable  to  use  the  term  sidcrite  —  long  ago  pro- 
posed by  Shepard  —  on  account  of  the  well  known  mineral  of  the  same 
name.  The  term  holosidcritc,  proposed  by  Danbree,  is  too  inaccurate,  since 
the  majority  of  the  specimens  are  not  wholly  iron. 

Siderolite  (o-t'S^pos,  \t0os)  —  a  stone  of  iron,  or  an  iron  rock  —  seems  to 
answer  better  than  any  other  term  for  the  specimens  I  have  included  under 
it  here,  and  if  the  transference  is  permitted  it  will  save  the  introduction  of  a 


new  name.* 


SECTION  II.  —  Pallasite. 

THIS  name  was  first  given  by  Gustav  Rose  to  a  class  of  meteorites,  of 
which  he  made  the  olivine  iron  rock  of  Krasnojarsk,  Siberia,  described  by 
Pallas  in  1776,  the  type.  Later,  Rose  separated  this  group  into  two  divis- 
ions —  pallasite  and  mesosiderite  —  the  latter  comprising  two  specimens 
only.t 

The  writer  proposes  to  restore  the  term  to  its  original  use ;  and  in  addi- 
tion, to  place  under  it  a  few  other  meteorites  and  those  terrestrial  rocks  that 
have  a  similar  composition  and  structure.  As  in  the  case  of  siderolite,  it  is 
not  intended  to  include  any  vein  stones,  but  only  original  and  eruptive 
rocks  of  this  character  and  their  derivatives. 

Of  this  group  or  species  there  will  be  given,  first,  descriptions  of  those 
nearest  the  siderolites  in  structure  and  composition,  passing  then  to  those 
nearer  and  nearer  allied  to  the  succeeding  species  —  peridotite. 

*  Maskelyne,  Phil.  Mag.,  1803  (4),  xxv.  49;   Rose,  Monatsber.  Berlin  Akad.,  1862,  pp.  551-558;  1863, 
pp.  30-34 ;  Shepard,  Amer.  Jour.  Sci.,  1807  (2),  xliii.  22-28. 

|  Monatsber.  Berlin  Akad.,  1862,  pp.  551-558;  1863,  pp.  30-34;  Abb.  Berlin  Akad.,  1803,  pp.  23-161. 


PALLASITE.  69 


The  Meteoric  Pallasites. 

Tucson,  Arizona. 

This  meteorite  is  represented  by  two  forms,  known  respectively  as  the  Carleton  and 
the  Ainsa  meteorites. 

The  Carleton  pallasite  is  composed  of  quite  a  compact  sponge  of  iron,  containing 
minute  rounded  grains  of  olivine  (?)  Some  schreibersite  in  black  angular  grams  also 
occurs.* 

The  Ainsa  pallasite  is  composed  of  a  compact  metallic  sponge,  the  minute  cells  of 
which  are  filled  by  a  white  siliceous  mineral  in  rounded  grains.  These  grains  are  arranged 
in  rude  lines,  giving  to  the  iron  an  appearance  somewhat  resembling  that  produced  by 
ttuidal  structure.  From  the  torn  and  broken  surface  of  a  specimen  in  Professor  Whit- 
ney's collection  a  number  of  silicate  grains  were  removed  by  a  needle-point,  imbedded  in 
Canada  balsam,  covered  and  examined  under  the  microscope.  Most  of  the  fragments 
present  the  optical  characters  of  olivine,  and  some  contain  bubble-bearing  stone  cavities, 
arranged  in  irregular  lines,  the  same  as  are  the  fluid  cavities  in  quartz.  A  few  of  the 
broken  grains  presented  the  polarization  characters  of  non-striated  meteoric  feldspar,  but 
two  fragments  were  seen  which  showed  the  polysynthetic  twinning  characteristic  of  pla- 
gioclase. 

Both  of  the  above  pallasites,  when  sawn  or  polished,  present  a  more  or  less  compact 
appearance,  like  the  common  siderolites,  and  it  is  only  where  the  Ainsa  meteorite  has 
been  forcibly  torn  apart,  after  being  partially  sawn,  that  its  true  structure  can  be  seen. 
Since  the  sawn  and  polished  surfaces  of  the  irons  are  such  poor  guides  to  their  structure, 
it  may  be  that  some  other  irons  now  classed  with  the  siderolites  belong  here. 

While  the  silicates  f  of  the  Ainsa  pallasites  are  nominally  clear  and  transparent,  a 
number  of  the  fragments  have  been  stained  to  a  yellowish  brown,  owing  to  the  oxidation 
of  the  iron. 

Hemalya,  Tarapaca,  Peru. 

This  rock,  as  represented  by  a  specimen  deposited  in  the  collections  of  the  Boston 
Society  of  Natural  History,  is  largely  composed  of  iron,  having  irregular  cavities  filled 
with  silicates,  which  are  considerably  decomposed  in  places. 

Mr.  R.  P.  Greg  states  of  a  specimen  in  his  possession,  that  its  cavities  were  found  to 
contain  pure  lead,  a  very  hard,  grayish-black,  semi-metallic  mineral,  and  a  yellowish- 
brown  one  of  an  earthy  texture,  and  insoluble  in  acids.  Sometimes  the  lead  only  par- 
tially filled  the  cavities,  but  at  others  it  entirely  filled  them,  some  being  large  as  a  pea.J 

The  specific  gravity  of  this  pallasite  was  found  to  be  about  6.50. 

Berdjansk,  Russia. 

According  to  Hiriakoff,  this  is  composed  of  an  iron  sponge,  with  fine  grains  of  olivine 
and  troilite,  and  on  etching  shows  Widinannstattian  figures.  Specific  gravity,  6.63.  § 

*  Whitney  and  Brush,  Proc.  Cal.  Acad.  Sci.,  1863,  iii.  30-35  ;  Haidinger,  Sitz.  Wien.  Akad.,  1863,  xlviii. 
(2),  301-308. 

t  Whitney,  Proc.  Cal.  Acad.  Sci.,  1863,  iii.  48-50. 

J  Phil.  Mag.,  1S55  (4),  x.  12-14. 

j  Geol.  Foren.  Forhandl.,  1878,  iv.  72  ;  Neues  Jahr.  Min.,  1878,  pp.  653,  654. 


70  THE  SIDEEOLITES   AND   PALLASITES. 

Deesa,   Chili. 

This  is  composed  of  a  compact  iron  sponge,  containing  inclosed  silicates.  Dr.  S. 
Meuuier  detected  in  it  troilite,  schreibersite,  graphite,  olivine,  hypersthene,  pyroxene, 
eustatite,  chromite,  etc.  Specific  gravity  varies  from  6.10  to  6.24,  but  no  satisfactory 
analysis  exists  of  it  as  a  whole.* 


Atacama,  Bolivia. 

The  rock  found  in  the  Desert  of  Atacama,  Bolivia,  is  described  as  a  cellular  or  spongy, 
metallic  mass  ;  the  cells  filled  with  granular,  greenish-white  olivine.  The  cellular  spaces 
instead  of  being  rounded,  as  in  the  other  rocks  of  this  species,  are  stated  to  be  angular. 
An  analysis  of  this  rock  as  a  whole  is  much  to  be  desired,  although  a  rough  approxima- 
tion is  given  in  the  list  of  analyses.  A  correct  chemical  analysis  would  probably  show 
this  to  be  more  basic  than  the  Pallas  rock  of  Siberia,  f 

A  specimen  in  the  Harvard  College  Mineralogical  Cabinet  is  probably  from  the  same 
pallasite.  This  shows  a  very  coarse  sponge  of  iron,  holding  angular  and  rounded  grains 
of  olivine.  The  olivine  is  yellowish-green  in  color  —  the  yellowish  tint  owing  in  part  to 
a  ferruginous  staining.  The  coarseness  of  the  iron  sponge  allies  this  more  nearly  than 
any  of  the  other  pallasites  seen,  except  that  from  Tarapaca,  to  the  siderolites. 

On  one  side  it  shows  a  surface  closely  resembling  an  ordinary  slickenside,  hut  on 
another  side  is  to  be  seen  the  remains  of  a  fused  crust  —  the  common  mark  of  a  meteor- 
ite. Some  pyrrhotite  was  seen  in  this  rock. 

Figure  1,  Plate  I.,  is  from  a  tracing  made  from  the  polished  surface  of  this  specimea 
Owing  to  the  dulness  of  the  polished  face  —  the  polishing  having  been  done  many  years 
ago  —  it  was  impracticable  to  get  the  outlines  exact.  The  general  structure  is  well 
shown  for  the  spongy  metallic  iron,  hut  the  olivine  grains  are  far  more  angular,  as  a  rule, 
than  the  figure  represents  them  to  be. 

Specimens  of  an  Atacama  meteoric  iron  in  the  Mineralogical  Cabinet,  received  from 
Professor  I.  Domcyko,  show  that  this  formed  a  metallic  sponge  holding  olivine.  Only 
traces  of  the  olivine  are  left,  and  beyond  it  nothing  can  be  told  regarding  the  silicates 
that  might  have  been  contained  in  this  sponge.  Some  pyrrhotite  was  seen.  This  con- 
tains less  iron  probably  than  the  Pallas  iron. 

Another  specimen  of  Atacama  iron  in  the  same  Cabinet,  received  from  a  Mr.  Clay,  of 
Philadelphia,  is  similar  to  that  figured  (PI.  I.  fig.  1),  but  the  sponge  is  not  so  coarse, 
and  the  olivine  is  more  abundant.  This  mineral  is  considerably  decomposed,  and  the 
iron  much  oxidized. 

Biiburg,  Prussia. 

A  coarse  sponge  of  iron,  containing  in  its  cells  light-greenish-brown  olivine.  The 
only  specimen  seen  by  the  writer  somewhat  resembles  the  Atacama  meteorite,  but,  per- 
haps, contains  even  more  iron. 

*  Daubree,  Comptes  Rendus,  136S,  Ixvi.  571,  572  ;  Meuuier,  Cosmos,  1869  (3),  v.  552-556,  579-586, 
612-019. 

f  Traus.  Roy.  Soc.  Ediu.  1831,  xi.  223-228  ;  Clark,  Metallic  Meteorites,  1851,  pp.  17-19. 


PALLASITE.  71 


Hommoney   Creek,  Buncombe   Co.,  North   Carolina. 

A  coarse  cellular  mass  of  nickeliferous  iron,  with  most  of  the  observed  cells  empty 
but  a  few  containing  dull,  yellowish-gray  divine  grains.  The  iron  exhibits,  on  etching, 

Widmaimstuttiaii  figures.* 

Singhur,  India. 

The  pallasite  found  at  Singhur,  Deccan,  India,  was  from  a  basaltic  hill.  It  is 
described  as  a  vesicular  mass  of  iron,  with  the  cavities  either  empty  or  else  containing 
"small,  yellowish-white,  earthy-looking  bodies,  about  the  size  of  peas"  —  olivine  (?). 
No  satisfactory  analysis  of  this  rock  has  been  made.f 

Its  occurrence  is  similar  to  that  of  the  iron  from  Disco,  Greenland,  and  it  may  be  of 
like  terrestrial  origin. 

Forsyth,  Taney  Co.,  Missouri. 

A  white,  sponge-like  mass  of  nickeliferous  iron  containing  greenish  olivine,  the  latter 
being  more  abundant  than  the  former.J  Specific  gravity,  4.46. 

Anderson,  Hamilton  Co.,  Ohio. 

This  pallasite,  which  may  properly  be  called  the  Little  Miami  meteorite,  was  found  on 
an  altar  in  one  of  the  earthworks  now  being  explored  in  Anderson  Township,  in  the  Lit- 
tle Miami  Valley,  Ohio.  This  was  placed  in  the  hands  of  Dr.  L.  P.  Kinnicutt,  for  analy- 
sis, by  Mr.  F.  W.  Putnam,  the  curator  of  the  Peabody  Museum  of  Archeology,  into  whose 
possession  it  had  come.  The  polished  surface  shows  a  coarse  sponge  of  iron,  holding, 
according  to  Dr.  Kinnicutt,  olivine,  brouzite,  and  an  unknown  mineral.  In  the  section 
figured  in  Dr.  Kinnicutt's  report,  the  iron  appears  to  predominate  over  the  silicates,  but 
taking  the  mass  as  a  whole  the  two  form  about  equal  bulk.  In  structure  it  closely 
resembles  the  Pallas  iron,  its  oliviue  grains  being  as  a  rule  rounded,  and  not  so  angular 
as  the  Atacama  pallasite.  The  olivine  forms  the  chief  portion  of  the  siliceous  material. 
The  specific  gravity  of.  the  mass  is  4.72.  The  etched  surfaces  show  the  Widmannstattian 
figures.  Analyses  of  the  iron  and  of  the  olivine  were  given  by  Dr.  Kinnicutt,  and  from 
this  a  rough  approximation  is  given  of  the  composition  of  the  mass  as  a  whole,  on  the 
supposition  that  the  iron  and  olivine  form  about  equal  portions  of  the  mass.  Since 
there  was  sufficient  material  it  seems  a  pity  that  no  complete  analysis  has  been  made.§ 

Krasnoj'arsk,  Siberia. 

The  Pallas  rock  is  formed  by  a  coarse  metallic  sponge,  whose  more  or  less  rounded 
cavities  are  filled  with  olivine.  This  sponge-like  structure,  or  one  approaching  it,  is 
characteristic  of  the  pallasites,  so  far  as  known.  No  complete  analysis  of  this  rock  has 
ever  been  published  that  the  writer  can  find,  except  an  old  one  of  Laugier,  ||  in  which  the 
iron  was  estimated  as  an  oxide. 

«  Shcpard,  Am.  Jonr.  Sci.,  1S47  (2),  iv.  79-82. 

f  Herbert  Giraml,  Edin.   New  Phil.  Jour.,  1849,  xlvii.  30,  57. 

J  Shepurd,  Am.  Jour.  Sci.,  1860,  (2)  xxx.  205,  2<ifi. 

§   Ann.  Hop.  IViibody  Mus.  Am.  Arc-li.,  188  t,  iii.  381-384. 

\l.'m.    \rad.  St.  Peters,  1870  (7)  xv.,  No.  6,  pp.  40,  4  plates.     Clark,  Metallic  Meteorites,  1851, 
pp.  15-17. 


72  THE   SIDEEOLITES    AND   PALLASITES. 

A  specimen  in  the  Harvard  Mineralogical  Cabinet  shows  the  same  characters  as  those 
given  in  the  various  papers  relating  to  this  iron,  including  even  the  parallel  minute  tubes 
in  the  olivine ;  hence  this  specimen  is  doubtless  authentic.  A  tracing  of  the  polished 
surface  of  this  specimen  is  given  in  figure  2,  Plate  I.  Of  course,  from  the  method  em- 
ployed, the  most  that  could  be  done  was  to  show  the  relation  of  the  iron  to  the  olivine ; 
for  the  pyrrhotite  could  not  be  separated  from  the  metallic  iron  in  making  the  tracing. 
This  apparently  has  less  iron  than  the  Atacama  pallasite. 

A  figure  of  a  polished  surface  of  the  Pallas  iron  has  been  given  by  Dr.  Carl  V. 
Schreibers,  which  seems  to  be  very  good,  except  that  the  olivine  has  been  too  highly 
colored.* 

Potosi,  Bolivia. 

Of  a  similar  character  is  the  Potosi  rock,  described  in  1839  as  a  meteoric  iron, 
"  cavernous,  filled  with  vacuities,  most  of  which  are  irregular,  but  some  have  the  form 
of  a  rhombic  dodecahedron ;  some  of  them  also  are  filled  with  a  greenish  vitreous  sub- 
stance, similar  to  the  olivine  of  Pallas."  f 

Brahin,  Russia. 

This  is  said  to  contain  somewhat  less  iron  and  more  olivine  than  the  Pallas  rock,  but 
otherwise  to  be  of  similar  composition  and  structure. 

RUiersgrun,  Saxony. 

The  Eittersgriin  pallasite  was  regarded  by  Weisbach  as  composed  of  30  per  cent  of 
nickeliferous  iron,  and  70  per  cent  of  an  unmetallic  brown  mass.  The  latter  was  said 
by  Winkler  to  be  composed  of  bronzite  (enstatite)  pyrrhotite,  schreibersite,  with  asmanite 
[tridymite]. 

Breithaupt  had  held  that  the  silicate  was  olivine.f 

In  Fouque  and  Levy's  Mineralogie  Micrographique  (PL  LV.  fig.  2)  is  given  a 
microscopic  section  of  the  Eittersgriin  rock  which  shows  that  it  is  composed  of  iron, 
diallage,  olivine,  and  augite.  The  olivine  contains  octahedrons  and  grains  of  pleonaste. 
The  structure  is  much  like  that  of  the  pallasite  from  Cumberland,  Rhode  Island 
(Cumberlandite). 

A  specimen  in  the  Harvard  College  Mineral  Cabinet  has  been  figured  from  the 
polished  surfaces.  In  this,  while  the  iron  in  places  forms  a  coarse  sponge,  in  other  parts 
it  is  much  less  in  amount  and  occurs  in  detached  irregular  grains.  Considerable  pyrrho- 
tite is  found  in  this,  forming  part  of  the  sponge  or  in  irregular  grains,  and  in  figuring 
(PI.  I.  figs.  3,  4)  has  not  been  separated  therefrom,  since  the  design  has  been  simply  to 
show  the  general  structure.  The  iron  where  etched  shows  the  usual  Widrnannstattian 
figures.  The  silicates  cannot,  of  course,  be  separated  through  the  examination  of  a 
polished  surface,  except  partially.  However,  this  specimen  appears  to  contain  consider- 
able well  marked  olivine. 

*  Stein-mid  Mctall-Massen,  1820,  Plate  VIII.  page  70. 

f  Phil.  Mag.,  1839  (3),  xiv.  394;  Chronique  Scientifique,  1839,  i.  31;  Ann.  Physik  Cliemie,  xlvii.  470; 
Neues  Jahr.  Min.,  1840,  p.  229. 

t  Nova  Acta  Leop.  Acad.  Halle,  1878,  xl.  333-382;  Berg.  Hiitt.  Zeit.,1862,  pp.  321,  322. 


PALLASITE.  73 

Since  this  specimen  was  figured  and  the  plate  in  the  hands  of  the  lithographer,  A. 
"\Vfisliin  h's  ;u •(•( unit  of  it,  with  the  accompanying  beautiful  plate,  has  been  received.* 

This  plate,  so  far  as  the  writer  can  judge,  shows  the  structure  exceedingly  well,  and, 
like  the  two  figures  drawn  by  him,  indicates  the  two  types  of  structure  in  this  meteorite. 
In  one  it  shows  the  sponge-like  character  of  the  iron,  holding  the  silicates  in  detached 
grains  and  masses ;  in  the  other  the  iron  appears  to  be  in  the  detached  grains  lying  in 
the  mass  of  silicates.  The  sponge-like  structure  shows,  however,  in  all  the  detached 
pieces  of  iron,  but  it  is  discontinuous. 

A  microscopic  examination  of  this  meteorite  has  been  made  by  Tschermak,  who 
states  that  the  asmanite  is  tridymite,  and  that  the  meteorite  is  composed  of  meteoric 
iron,  bronzite  and  tridymite.f 

Brcilenbach,  Bohemia. 

The  pallasite  from  Breitenbach  was  described  by  Prof.  K  S.  Maskelyne  in  1871. 
This  was  seen  to  be  composed  of  a  sponge-like  mass  of  nickeliferous  iron  with  some 
pyrrhotitc',  and  inclosing  in  its  cells  bronzite  (enstatite),  asmanite  (tridymite),  and  chro- 
rnite.  No  complete  analysis  has  been  made.J 

If  this  is,  as  has  been  claimed,  the  same  as  the  Rittersgriin  pallasite,  the  microscopic 
section  of  that  rock  given  by  Fouqui5  and  Levy  would  indicate  that  its  composition  was 
considerably  different  from  that  given  by  Maskelyne. 

Steinbach,  Saxony. 

The  structure  of  this  is  the  same  as  that  from  Eittersgriin,  and  these  two  with  the 
Breitenbach  pallasite  are  supposed  to  be  portions  of  the  same  mass. 

Atacama,  Chili. 

To  the  pallasites  also  belongs  a  meteorite  found  on  a  mountain  pass,  in  the  province 
of  Atacama,  Chili,  which  was  described  by  Prof.  Charles  A.  Joy.  This  rock  seems  to  be 
composed  of  an  irregular  sponge-like  mass  of  iron  holding  grains  of  olivine  and  enstatite 
or  labradorite,  most  probably  the  former.  § 

The  analysis  given  by  Professor  Joy  is  apparently  the  best  and  most  complete  yet 
made  of  any  of  the  pallasites. 

Sierra  de   Chaco,  Atacama,   Chili. 

According  to  Tschermak,  this  is  composed  of  an  iron  sponge,  containing  grains  of  iron 
and  silicate.  Plagioclase,  with  broad  twin  lamelhe,  is  quite  abundant,  and  contains 
numerous  inclusions,  of  bronzite,  pale  brownish  glass,  parallel  layers  of  fine  black 
needles,  etc.  Besides  the  plagioclase,  there  were  seen  greenish  grains  of  bronzite,  green- 
ish-gray rounded  grains  of  olivine,  with  dust-like  inclusions,  brownish  augite  grains, 
colorless  particles  of  tridymite,  some  supposed  cordierite,  and  a  brownish  glass.  This 
i-;  i  nnsidered  by  Tschermak  to  be  the  same  pallasite  as  that  analyzed  by  Joy  from 
Atacama. 

*  Dcr  Eisenmetoorit  von  Kittersgriin  im  saclisisclien  Erzgcbirgc,  Freiberg,  1876  ;  3  pp.  and  pkte. 

t  Sit/..  Wim.  AUl.,  1S83,  Ixxxviii.  (1),  313. 

J  I'liil.  Trans.,  1871,  pp.  359-365. 

§  Am.  Jour.  Sci.,  1864  (2),  xxxvii.  243-248. 

10 


74  THE   SIDEEOLITES   AND   PALLASITES. 

Newton   Co.,  Arkansas. 

A  coarsely  reticulated  or  sponge-like  mass  of  iron,  containing  in  its  cells  olivine  and 
enstatite  (?)  Chromite  and  pyrrhotite  also  occur. 

The  enstatite  is  of  a  greenish-gray  color,  and  more  or  less  stained  by  the  iron.  The 
olivine  is  in  part  colorless  and  in  part  stained  yellow  by  the  iron  oxide.  The  analysis 
does  not  afford  data  to  give  the  composition  of  the  rock  as  a  whole.*  The  specimens 
seen  indicate  that  it  is  closely  allied  to  the  peridotites,  but  probably  belongs  with  the 
pallasites,  with  which  it  is  here  placed. 

Mei/clloncs,  Atacama,  Bolivia. 

A  specimen  in  the  Harvard  Mineralogical  Cabinet  from  Meyellones,  Atacama,  Bolivia, 
shows  the  iron  in  irregular  fine  semi-sponge-like  masses.  Occasionally,  it  is  aggregated 
into  grains  from  one  to  three  quarters  of  an  inch  in  length,  but  in  general  the  grains  are 
minute.  The  iron  everywhere  is  rough,  pronged,  and  jagged.  The  silicates  cannot  be 
distinguished  from  one  another,  except  in  the  case  of  a  few  rounded  olivine  grains. 
This,  with  the  Hainholz  pallasite,  lies  near  the  peridotites  bearing  iron,  but  does  not 
seem  sufficiently  distinct  to  be  placed  in  a  different  species  from  the  pallasites. 

Hainholz,  Westphalia. 

The  Hainholz,  Westphalia,  pallasite,  while  much  finer  grained,  possesses  a  structure 
similar  to  those  portions  of  the  Ilittersgriin  pallasite  that  contain  the  least  iron,  and  this 
iron  in  detached  masses.  The  former  contains  irregular  grains  and  semi-spongiform 
masses  of  iron  and  pyrrhotite,  while  the  silicates  form  irregular  masses,  partly  included 
in  the  iron  and  partly  surrounding  it.  The  silicates  apparently  predominate,  and  show 
characters  much  like  those  of  the  Kittersgrtin  pallasite.  So  far  as  can  be  told  from  a 
macroscopic  study  of  this  specimen,  it  lies  near  the  Rittersgriin  meteorite,  but  forms  a 
connecting  link  between  it  and  the  peridotic  meteorites  containing  iron,  like  those  from 
Mezo-Madras,  Cabarras,  Iowa  Co.,  etc.  The  chemical  analysis,  if  it  is  a  fair  index  of  the 
general  composition  of  this  meteorite,  would  carry  it  into  the  peridotites.  This  pallas- 
ite lias  been  studied  microscopically  by  Tschermak,  who  states  that  its  included  silicates 
are  olivine  and  bronzite,  with  subordinate  amounts  plagioclase,  augite,  and  a  cordierite- 
like  mineral  The  olivine  grains  are  from  30  to  40  cm.  in  length,  and  contain  only  few 
inclusions.  The  bronzite  grains  are  smaller,  and  contain  inclusions  of  brown  glass  and 
black  grains.  The  plagioclase  shows  the  usual  twinned  structure  in  polarized  light,  and 
contains  grains  of  olivine  and  bronzite.  A  few  grains  of  augite  occur,  having  fine  dust- 
like  inclusions,  as  well  as  brown  glass  globules,  and  angular  black  grains.  Only  two 
grains  of  the  supposed  cordierite  were  seen.  All  the  larger  crystals  lie  in  a  groundmass, 
composed  of  the  same  minerals,  with  a  little  interstitial  brown  glass. f 

Lodran,  India. 

The  meteorite  from  Lodran,  India,  is  described  by  Tschermak  as  a  granular  mixture 
of  vitreous,  bluish-gray,  and  yellowish-green  grains,  between  which  steel-gray  and  yel- 

*  J.  Lawrence  Smith,  Mineralogy  and  Chemistry,  Louisville,  Ky.,  1873,  pp-  339-342. 
f  Sitz.  Wien.  Akad.,  1883,  kxxviii.  319-331. 


PALLASITE.  —  CUMBERLANDITE.  75 

lowish  metallic  particles  are  to  be  seen.  The  microscopic  and  chemical  examination 
showed  that  the  rock  was  composed  of  nickeliferous  iron,  pyrrhotite,  chromite,  olivine, 
and  hron/ite.  The  nickeliferous  iron  forms  the  cementing  mass,  in  a  fine  irregular  net- 
work. In  the  finer  meshes  lie  single  crystals,  and  in  coarser  portions  are  inclosed  aggre- 
gated grains  and  crystals  of  the  above  mentioned  minerals.  This  iron  is  of  a  very  light 
steel  gray  color,  and,  on  etching  its  surface,  shows  under  the  microscope  figures  somewhat 
similar  to  those  of  the  Senegal  iron. 

The  olivine  forms  more  or  less  perfect  crystals,  which  occur  both  in  the  iron  and  as 
inti-rgrowths  with  the  bronzite.  The  olivine  was  determined  by  the  crystallographic 
nira-iiiremriits  of  Professor  Viktor  von  Lang  to  be  of  the  same  form  as  basaltic  olivine. 
It  is  on  the  surface  of  a  bluish-gray  to  a  berlin-blue  color,  but  in  the  thin  section  pale 
green. 

Under  the  microscope  no  well  marked  cleavages  were  seen,  but  undulating  fissures 
parallel  to  the  basal  pinacoid  are  common.  Many  of  these  cracks  are  bordered  by  a  moss- 
like  black  mineral,  which  Tscherinak  regards  as  chromite,  arising  from  a  secondary  altera- 
tion of  the  olivine.  Judging  from  the  figure  given,  the  present  writer  would  agree  in 
this  particular  with  Tscherinak. 

The  bronzite  occurs  in  grains  and  irregular  crystals.  From  its  crystallographic  char- 
acters, as  determined  by  Von  Lang,  it  appears  to  be  enstatite,  the  same  as  the  bronzite 
in  the  Breitenbach  meteorite.  The  enstatite  has  an  asparagus-green  to  a  yellowish- 
green  color,  and  under  the  microscope  is  of  a  very  pale  green  shade.  It  is  traversed  by 
the  usual  cleavage  and  fissure  lines,  and  contains  inclusions  of  three  different  kinds.  The 
first  is  in  the  form  of  colorless  rounded  grains,  which  are  regarded  as  feldspar.  The  next 
class  of  inclusions  are  minute,  round,  black  particles,  which  are  referred  to  chromite. 
The  last  class  are  fine  hair-like  bodies,  like  those  commonly  seen  in  terrestrial  bronzite, 
but  whose  nature  was  not  determined  by  Tscherinak. 

The  pyrrhotite  was  seen  united  with  the  iron,  and  often  between  the  silicates  in  yel- 
low grains  having  a  metallic  lustre. 

The  chromite  occurs  in  black  crystals  and  grams,  possessing  a  strong  semi-metallic 
lustre.  The  planes  of  an  octahedron,  rhombic  dodecahedron,  and  tetragonal  triakis  octa- 
hedron were  observed  by  Von  Lang  upon  the  chromite  crystals.  It  was  found  in  small 
amounts  between  the  silicate,  and  also  in  the  iron.  For  a  fuller  description  and  the 
figures,  the  reader  is  referred  to  the  original  paper  with  its  accompanying  plate.*  It  is 
doubtful  whether  this  meteorite  should  be  placed  here,  or  classed  with  the  peridotites. 


VARIETY.  —  Cumberlandite. 

Iron  Mine  Hill,   Cumberland,  RJiode  Island. 

No.  998.  A  dark  resinous,  almost  black,  crystalline  groundmass,  holding,  porphy- 
ritically  inclosed,  long,  striated,  glassy,  and  milky  plagioclase  crystals.  Powder  strongly 
magnetic.  This  rock  has  Ven  exposed  on  one  side  to  weathering,  and  shows  a  dark 
brown  mass  holding  grains  of  magnetite,  and  gives  an  earthy  yellow  streak.  In  some  of 
the  unaltered  portions,  the  groundmass  has  the  oil-green  color  of  olivine.  The  fracture 

«  Sitz.  Wien.  Akad,  1S70.  Ixi.  (-2),  405-175. 


76  THE   SIDEROLITES   AND   PALLASITES. 

is  rough,  splintery,  and  conchoidal.  The  rock  gelatinizes  with  hydrochloric  acid,  even 
in  the  cold,  and  gives  a  titanium  reaction. 

Section :  A  granular  groundmass,  composed  of  olivine  and  magnetite,  holding  porphy- 
ritically  inclosed  feldspar  crystals.  The  magnetite  forms  more  or  less  connected  spongi- 
form  irregular  masses.  The  olivine  is  in  crystals  and  grains,  united  directly  without  any 
cement,  and  occupies  the  cells  and  interspaces  hetween  the  magnetite  masses.  Grains  of 
magnetite  are  of  frequent  occurrence  in  the  olivine.  The  olivine  is  traversed  by  numer- 
ous fissures,  and  the  majority  of  the  grains  show  a  well  marked  cleavage.  The  fissures 
usually  have  a  ferruginous  staining.  Besides  this,  the  olivine  is  comparatively  clear 
and  unaltered,  exhibiting,  however,  in  connection  with  the  feldspar,  a  greenish  alteration- 
product. 

The  plagioclase  is  in  grains  and  irregular  masses,  which  occasionally  send  tongues  out 
into  the  olivine  magnetite  mass.  It  shows  well  marked  cleavage  planes,  and  is  some- 
what kaolinized  along  those  lines,  otherwise  the  feldspar  is  clear  and  glassy.  In  polar- 
ized light  the  larger  feldspar  masses  were  seen  to  be  made  up  of  several  polysynthetic 
individuals.  Some  small  microscopic  grains  of  feldspar  are  scattered  in  the  rock  mass, 
but  as  a  rule  most  of  it  is  in  large  crystals,  clearly  seen  macroscopically.  A  few  reddish- 
brown  biotite  flakes  were  observed  in  the  feldspar. 

The  sponge-like  structure  of  the  magnetite  is  the  same  as  that  of  the  iron  in  the  sup- 
posed meteoric  pallasites,  and  in  a  similar  manner  contains  the  inclosed  olivine.  As 
would  be  expected,  as  a  rule,  in  any  iron  coming  to  the  surface  of  the  earth  in  a  heated 
condition  (eruptive),  the  iron  in  this  rock  has  suffered  the  first  stage  of  oxidation,  and  is  a 
magnetite.  The  writer  regards  the  state  of  the  iron  (its  alteration)  of  but  little  conse- 
quence, so  long  as  the  structure  and  general  chemical  and  mineralogical  composition 
remain  the  same.  This  section  is  figured  in  Plate  I.  figure  5. 

In  this  figure  the  black  portions  represent  the  magnetic  iron,  and  the  light  yellow 
and  whitish  portions  the  fissured  oliviue. 

No.  999  is,  both  in  the  hand  specimen  and  section,  similar  to  the  preceding. 

No.  1000.  This  is  weathered  to  a  slight  extent  only,  and  shows  the  same  characters 
as  the  unweathered  portions  of  Nos.  998  and  999.  The  sections  show  the  same  relation 
of  the  magnetite  and  olivine  as  in  the  preceding.  The  latter  mineral  contains  many 
grains  and  crystals  of  magnetite,  and  is  much  fissured.  These  fissures  are  filled  largely 
with  magnetite  granules  and  air  cavities.  It  is  stained  yellowish  and  greenish  in  places, 
and  was  seen  in  some  portions  to  have  been  changed  into  a  greenish  aggregately  polariz- 
ing mass. 

The  feldspar  is  clear  throughout  the  greater  portion  of  the  mass,  but  in  parts  is 
kaolinized,  and  contains  fluid  and  air  cavities.  This  mineral  in  one  section  is  seen  to  be 
in  small  masses,  as  well  as  large,  and  holding  such  relations  to  the  olivine  and  magnetite 
that  it  leaves  no  doubt  that  it  is  a  later  crystallization  than  either  of  the  other  minerals. 
A  small  fracture  extends  across  a  portion  of  the  section,  through  the  feldspar  and  olivine 
grains,  forming  a  miniature  vein.  The  materials  deposited  in  this  vein  vary  according  to 
its  position,  whether  in  the  feldspar  or  in  the  olivine,  but,  at  the  contact  of  the  two 
minerals,  contains  ingredients  derived  from  both.  This  might  be  taken  on  a  miscroscopic 
scale  to  illustrate  the  variation  of  veins  in  passing  from  one  rock  to  another.  In  the 
olivine  the  vein  is  filled  with  serpentinous  material,  but  in  the  feldspar  with  silicious. 


PALLASITE.  —  CUMBERLANDITE.  77 

Biotite  occurs  as  a  secondary  product  in  connection  with  the  magnetite.  It  is  seen 
formim,'  a  fringe  about  the  latter,  or  joined  on  to  some  of  its  prongs,  extending  out  into 
the  oliviue  grains.  The  color  is  dark  reddish  brown,  and  the  mineral  shows  strong 
didiroism  and  well  marked  cleavage. 

In  the  magnetite  tilling  some  cavities  and  fissures,  a  dark  green  isotropic  mineral,  of 
irregular  outline  and  unknown  characters,  was  observed.*  This  is  regarded  by  myself 
as  a  secondary  mineral,  formed  like  the  biotite,  in  connection  with  the  magnetite.  In 
another  section  considerable  earthy  yellowish  green  and  green  aggregately  polarizing 
alteration  products  were  observed  in  connection  with  the  feldspar  and  oliviue. 

In  all  of  the  preceding  sections  the  olivine  is  the  predominating  mineral.  The  feld- 
spar crystals  are  confined  to  one  side  of  the  hill  composed  of  this  rock,  and  they  are 
therefore  local,  and  not  to  be  regarded  as  characteristic  of  the  rock  as  a  whole. 

No.  1005,  from  the  same  locality  as  the  preceding,  but  nearer  the  middle  of  the  hill, 
shows  a  dark  granular  and  crystalline  groundmass  in  which,  under  a  lens,  can  be  seen 
olivine  in  yellowish  green  grains,  magnetite,  and  clear  greenish  glassy  actinolite  with  a 
well  marked  cleavage.  Dark  green  serpentinous  masses  occur  in  the  rock  in  irregular 
vein-like  and  nodular  forms.  The  rock  weathers  to  a  dull  brownish  gray  surface,  while 
immediately  beneath  the  surface  crust  the  olivine  is  decomposed  to  a  yellowish  brown 
ferruginous  earth. 

Section :  The  general  structure  of  the  section  is  the  same  as  that  of  No.  998,  without 
the  feldspar;  that  is,  like  the  more  compact  portions  of  the  section  of  that  specimen. 
A  certain  amount  of  alteration,  however,  has  taken  place  here.  This  specimen,  like  all 
except  those  in  the  immediate  vicinity  of  No.  1000,  is  free  from  feldspar.  The  olivine 
grains  are  now  separated  in  the  majority  of  cases  from  the  magnetite  sponge  by  a  narrow 
liliu  of  a  pale  greenish  actinolitic  alteration  product,  which  also  separates  these  grains 
from  one  another.  The  same  product  in  places  traverses  fissures  in  the  olivine,  and 
replaces  some  of  the  smaller  grains.  The  olivine  further  presents  in  part  a  cloudy,  smoky 
appearance,  arising  from  a  dark-colored  staining,  extending  in  fine  lines  parallel  to  a 
crystallographic  axis.  This  clouding  extends  sometimes  over  part  only,  and  at  other 
times  over  the  entire  crystal.  A  greenish  yellow  serpentine  replaces  the  olivine  to  some 
extent,  and  extends  in  vein-like  forms  across  part  of  the  crystals.  The  actinolite  in  the 
section  is  in  minute  elongated,  irregular  crystals,  usually  forming  an  interlocked  mass. 
The  olivine  contains  fluid,  glass,  and  gas  inclusions,  as  well  as  detached  secondary 
actinolite  crystals. 

No.  1002  is  macroscopically  almost  identical  with  No.  1005 ;  but  microscopically, 
its  olivine  is  less  in  amount,  and  the  actinolite  in  better  formed  and  larger  crystals. 
In  many  portions  of  the  section  the  latter  mineral  appears  in  long-bladed  crystals  with 
well  marked  longitudinal  cleavage.  In  other  cases  when  the  crystals  are  cut  across  they 
show  the  characteristic  amphibole  cleavage  rhombs.  They  are  colorless,  and  exhibit  very 
brilliant  polarization  colors.  Some  of  the  altered  portions  of  the  section  are  of  a  pale 
greenish  hue,  and  formed  of  an  interlaced  mass  of  fibres  and  non-polarizing  particles  — 
the  fibres  being  apparently  actinolite.  Other  portions,  more  coarsely  crystalline,  show 
dichroLsm,  varying  from  a  pale  green  to  a  pale  yellow. 

*  Dr.  (i'u.  II.  \Villiams  thought  that  this  might  be  hcrcynitc,  a  mineral  which  he  had  been  especially 
studying.     Specimens  of  the  rock  were  placed  in  his  hands,  but  owing  to  the  small  amount  of  this  mineral, 
!icr  with  its  high  specific  gravity,  lie  was  unable  to  isolate  it  from  the  magnetite. 


78  THE   SIDEEOLITES   AXD   PALLASITES. 

The  magnetite  has  diminished  in  amount,  and  for  the  most  part  forms  a  discontinuous 
sponge.  This  discontinuity  appears  to  have  arisen  from  the  solution  of  the  magnetite 
along  the  borders  of  its  fissures  and  edges,  which  solution  in  some  places  has  removed 
nearly  the  whole  of  this  mineral. 

The  removed  portions  are  replaced  by  actinolitic  material.  The  olivine  is  generally 
surrounded  by  a  border  of  actinolitic  material,  whose  general  relation  is  shown  in  Plate  II. 
figure  1,  the  black  portion  representing  the  magnetic  sponge,  the  brownish  parts  the 
smoky,  fissured  olivine,  and  the  gray  and  white  portions  the  secondary  actinolite. 

In  this  the  actinolite  band  is  represented  by  the  uncolored  portion  surrounding  the 
olivine,  and  in  its  turn  inclosed  by  the  magnetite.  Little  granules  remain  in  the  actin- 
olitic material,  part  of  which  are  shown  in  the  drawing.  The  olivine  as  before  is 
"  smoky,"  marking  apparently  the  first  stage  in  its  alteration. 

Nos.  1007  and  1008  are  both  in  the  section  and  hand  specimen  similar  to  the  pre- 
ceding number,  only  in  some  portions  the  alteration  has  not  extended  quite  so  far. 

No.  1006  is  somewhat  more  changed  than  No.  1002.  The  section  is  partially 
crossed  by  greenish  actinolitic  material,  which  replaces  nearly  all  of  the  original  matter. 
In  other  portions  the  original  structure  still  remains,  the  olivine  being  partly  replaced 
by  actinolite,  etc.  The  centres  of  the  olivine  are  in  part  only  dark  smoky-brown,  but 
in  others  are  altered  to  a  reddish-brown  serpentinous  like  product. 

The  section  is  stained  by  a  greenish,  yellowish,  and  brownish  product  in  many  places. 
This  section  serves  as  the  last  link  in  the  chain  connecting  the  specimens  which  contain 
unaltered  olivine  with  those  in  which  the  olivine  is  entirely  changed. 

No.  1001  is  from  the  same  locality  as  No.  1000,  but  nearer  the  centre  of  the  hill. 
This  is  a  dark  greenish  black  rock,  showing  a  greenish  serpentinous  groundmass  sprinkled 
with  titaniferous  magnetite.  Rounded  and  irregular  patches  of  green  serpentine,  com- 
paratively free  from  the  magnetite,  are  irregularly  distributed  in  the  groundmass.  In 
weathering,  the  magnetite  is  left  projecting  in  a  cellular  sponge-like  mass. 

Section :  This,  like  the  preceding,  is  composed  of  an  irregular  sponge-like  mass  of 
magnetite,  with  the  interspaces  filled  with  pale  greenish  and  grayish  mineral  matter. 
While  the  structure  of  the  section  is  essentially  the  same  as  that  of  Nos.  998,  999,  and 
1OOO,  the  olivine  is  entirely  replaced  by  serpentine.  The  forms  of  the  olivine  grains 
remain  the  same,  and  the  fissures  by  which  they  were  traversed  are  marked  by  magnetite 
grains  arranged  in  lines  extending  through  the  serpentine.  With  a  low  power  hi  com- 
mon light  the  section  is  almost  undistingtiishable  from  one  containing  unchanged  olivine. 
With  a  higher  power,  or  in  polarized  light,  the  fibrous  structure  of  the  serpentine  shows 
itself.  The  polarization  colors  are  dull,  and  the  platy  fibrous  masses  show  some  resem- 
blance to  talc,  as  well  as  being  obscured  when  the  fibres  are  parallel  to  a  diagonal  of  the 
crossed  nicols.  The  original  fissures  of  the  olivine  show  well  both  in  common  and  polar- 
ized light.  Magnetite  is  included  in  the  serpentine,  not  only  in  original  grains,  as  seen 
in  the  olivine  of  No.  998,  but  also  in  scattered  dust-like  granules  and  irregular  masses, 
or  in  lines  along  the  fissures.  The  latter  magnetite  is  apparently  a  secondary  product 
formed  during  the  conversion  of  the  olivine  to  serpentine.  The  main  magnetite  sponge- 
like  mass  is  not  quite  so  closely  united  as  in  No.  998,  neither  does  it  occupy  so  great  an 
extent  of  the  section ;  i.  e.,  the  percentage  of  magnetite  is  somewhat  smaller  in  this  por- 
tion of  the  hill,  and  continues  less  in  all  parts  of  the  hill  not  immediately  adjacent  to 


PALLASITE.  —  CUMI5ERLANDITE.  79 

the  porphyritic  feldspar  portion,  so  far  as  the  writer  has  observed  The  structure  of  this 
section  is  shown  in  1'late  I.  figure  6.  In  this  the  structure  of  the  altered  fissured  olivine, 
closely  resembling  the  olivine  of  figure  5,  is  clearly  shown. 

No.  1003  shows  more  serpentine  characters  than  No.  1001,  having  less  iron  and 
more  of  the  irregular  serpentine  masses.  In  the  section  the  characters  are  essentially 
the'  same  as  those  of  No.  1001.  Some  talc  in  fine  scales  aggregated  together  was  seen 
towards  the  interior  of  the  larger  serpentinized  oliviues,  and  in  the  macroscopically  visi- 
ble serpentine  masses  hefore  mentioned.  The  serpentine  in  these  masses  is  pale-green 
and  isotropic.  The  serpentine  replacing  the  olivine  shows  the  same  fibrous  character 
as  No.  1001,  but  the  structure  is  better  marked,  and  the  fibrous  plates  polarized  with 
brilliant  colors.  In  portions  of  the  section  considerable  actinolite  was  observed. 

X<  's.  1004,  1009,  1010,  and  1011  are  from  the  side  of  the  hill  opposite  to  No. 
1000,  and  with  the  preceding  specimens  show  the  gradual  change  from  one  side,  on 
which  is  to  be  found  such  material  as  No.  1000,  to  those  masses  which  have  suffered 
very  great  alteration.  Part  show  ochery  patches  of  ferruginous  alteration.  In  general, 
the  sponge-like  structure  of  the  magnetite  still  remains,  and  besides  this  the  interspaces 
are  variously  filled  with  talc,  serpentine,  actinolite,  etc.  —  the  serpentinous  material  pre- 
dominating over  the  others.  Owing  to  the  extreme  alteration,  some  of  these  specimens 
have  developed  an  imperfect  fissile  or  laminated  structure,  which  might  be  mistaken  for 
bedding  planes. 

No.  1012.  This  was  from  an  exposure  near  No.  1011,  but  separated  from  it  by  a 
rivulet,  and  its  connection  with  the  other  described  masses  could  not  be  shown  in  the 
field.  This  rock  is  much  jointed,  presenting  an  imperfect  fissile  structure,  and  is  of  a 
dark  green  color,  with  yellowish-brown  ochery  spots  of  decomposition.  On  the  weath- 
ered surface,  the  magnetite  shows  the  irregular  sponge-like  structure  so  characteristic 
of  all  these  rocks.  The  character  of  the  section  is  like  that  of  those  last  described,  but 
with  the  addition  to  its  alteration-products  of  considerable  dolomite.  I  have  no  hesita- 
tion in  declaring  my  opinion,  from  the  microscopic  characters  of  this  specimen,  that  this 
outcrop  belongs  to  the  same  formation  as  the  hill  itself. 


The  specific  gravity  of  the  Cumberland  pallasite  varies  according  to  the 
state  of  the  rock  —  whether  altered  or  unaltered.  Dr.  Charles  T.  Jackson 
states  that  it  varies  from  3.82  to  3.88.  Mr.  J.  E.  Wolff,  Assistant  in  Geology 
in  Harvard  College,  kindly  made  some  determinations  for  me.  The  specific 
gravity  of  No.  998  was  found  to  be  4.06  and  4.005.  The  former  determina- 
tion was  made  from  a  fragment  containing  almost  no  feldspar,  while  the 
latter  was  made  from  one  containing  considerable.  .Again,  a  specific  gravity 
determination  of  No.  1001  gave  as  a  result  3.56,  and  of  No.  1003,  3.55. 

The  two  latter  determinations  were  made  from  the  more  highly  altered 
portions  of  the  rock. 

Owing  to   the   various  alterations  that  this  Cumberland  rock  shows,  it 


80  THE   SIDEROLITES   AND   PALLASITES. 

would  be  very  interesting  if  chemical  analyses  should  be  made  of  the  differ- 
ent portions,  in  order  to  ascertain  what  changes  in  the  ultimate  chemical 
composition  have  taken  place.  They  should  be  made  from  material  micro- 
scopically examined,  so  that  the  specific  gravity  and  chemical  and  miner- 
alogical  characters  could  be  coordinated.  The  diminished  specific  gravity  of 
the  more  highly  altered  portions  of  this  rock,  as  above  determined,  would 
indicate  that  considerable  changes  had  taken  place  in  the  chemical  composi- 
tion of  the  rock  as  a  whole.  Further,  an  examination  should  be  made  of 
the  least  altered  portions  of  this  and  all  similar  rocks,  for  the  purpose  of 
ascertaining  if  they  contain  any  of  the  elements  so  commonly  found  in 
meteoric  pallasites  and  siderolites.  It  is  not  impossible  that,  on  boring,  in 
depth  some  of  the  iron  might  be  found  in  the  native  state  instead  of  being 
entirely  oxidized. 

This  rock  has  been  used  as  an  iron  ore,  for  an  historical  account  of  which 
the  reader  is  referred  to  previous  papers  of  the  writer.* 

The  additions  and  changes  made  in  these  descriptions  to  those  already 
published,  have  been  caused  by  the  preparation  and  examination  of  other 
sections,  thus  making  the  work  more  complete.  At  the  time  the  former 
descriptions  were  written,  the  writer  assigned  this  rock  to  the  peridotites  — 
the  most  basic  olivine  rock  of  terrestrial  origin  then  known.  Although  its 
relation  to  the  meteorites  was  recognized,  yet,  since  the  present  study  of  the 
meteorites  themselves  was  not  undertaken  until  February,  1882,  the  writer 
may  be  pardoned  for  not  earlier  perceiving  its  distinctness  from  the  peri- 
dotites, properly  so  called.  It  is  now  regarded  as  a  pallasite  in  which  the 
iron  has  been  oxidized  —  probably  at  the  time  the  rock  was  formed.  The 
writer  holds  that  the  rock  is  eruptive,  although  no  proof  beyond  its  micro- 
scopic characters  has  been  obtained ;  and  if  its  relations  to  the  country  rock 
should  be  found  to  be  non-eruptive  ones,  then  this  view  would  have  to  be 
abandoned. 

If  it  is  necessary  to  have  a  distinct  name  to  indicate  the  pallasites  above 
described,  in  which  the  iron  is  oxidized,  the  writer  would  propose  that  of 
Cumber landite,  from  the  locality  in  which  it  occurs  in  Rhode  Island.  He 
would  have  preferred  that  of  Talergite,  from  the  earlier  described  rock  from 
Taberg,  Sweden,  if  that  name  had  not  already  been  in  current  use  in  min- 
eralogy. 

In  this  direction  a  vast  field  exists  in  the  study  of  iron-bearing  rocks 

*  Bull.  Mus.  Couip.  Zoul.,  1881,  vii.  183-187;  Proc.  Bost.  Soc.  Nat.  Hist.,  1881,  xxi.  195-197. 


I'AIJASITE.— CUMBERLANDITE.  81 

containing  actinolite,  serpentine,  etc. ;  and  the  question  of  the  formation  of 
certain  schistose  rocks  by  inetamorphism  of  these  terrestrial  pallasites  is  an 
interesting  one. 

A  .similar  structure  to  that  of  this  Rhode  Island  pallasite  has  been 
reported  in  some  New  York  and  Canada  iron-bearing  rocks. 

Taberg,  Sweden. 

Of  a  similar  character  to  the  Cumberland  pallasite  is  the  rock  from  Taberg,  Sweden, 
so  long  known  and  so  well  described  by  Messrs.  Sjoren  and  Tornebohm.* 

The  section  in  the  collection  purchased  from  Kichard  Fuess  of  Berlin  shows  an 
imperfect  sponge-like  mass  of  magnetite,  holding  olivine  and  feldspar. 

The  olivine  is  much  fissured  and  traversed  along  the  fissures  by  serpentine  and  mag- 
netite bands,  while  in  places  it  is  entirely  replaced  by  the  secondary  serpentine. 

The  feldspar  is  in  irregular,  somewhat  kaolinized  masses,  holding  olivine  and  mag- 
netite grains.  The  feldspar  polarizes  with  a  polysynthetic  structure. 

A  reddish-brown  secondary  biotite  is  associated  with  the  magnetite,  but  is  more 
abundant  than  it  is  in  the  Cumberland  rock. 

For  the  full  description  of  this  rock  the  reader  is  referred  to  the  original  papers 
above  mentioned.  This  rock  is  figured  on  Plate  II.  figures  2  and  3.  Figure  2  shows  the 
sponge-like  magnetite  with  the  inclosed  olivine,  while  figure  3  shows  a  more  highly 
nil  rod  portion  of  the  same  section  in  which  the  magnetite  has  partly  disappeared  and 
the  silicates  contain  more  ferruginous  material.  The  reddish-brown  portions  are  the 
secondary  mica,  usually  associated  with  or  replacing  the  magnetite. 

The  pallasites  may  then  be  described  in  general  terms  as  composed  of  a 
ferruginous  sponge-like  or  semi-sponge-like  mass,  holding  olivine  with  or 
without  feldspar,  enstatite,  diallage,  augite,  and  chromite,  or  spinel  min- 
erals. The  sponge  is  formed  either  by  native  iron  with  pyrrhotite,  or  by 
their  secondary  products,  like  magnetite. 

The  alteration  of  these  original  materials  gives  rise  to  serpentine,  chro- 
mite (?),  biotite,  actinolite,  etc. 

The  general  structure  of  the  Cumberlandite  from  Rhode  Island  may  be 
summed  up  as  follows :  In  the  least  altered  condition  it  shows  a  dark  resi- 
nous, crystalline,  splintery  and  compact  mass,  holding  porphyritically  inclosed 
feldspars,  which,  although  characteristic  of  one  portion  of  the  locality,  are 
not  essential.  This  rock  passes  into  a  form  destitute  of  feldspar,  but  having 
the  same  groundmass,  which  contains  patches  of  a  dark-green,  fine-grained 
alteration-product,  which  holds  a  similar  relation  to  the  groundmass  as  the 
feldspar  in  the  preceding.  In  the  succeeding  forms  the  resinous  groundmass 

»  Geol.  Forcn.  Forhan.,  1876,  iii.  42-62;   1881,  v.  610-619;  1S82,  vi.  264-267;  Neues  Jahr.  Miti., 
,  pp.  434,435;  1882,  ii.  66,67. 

11 


82  THE  SIDEEOLITES   AND   PALLASITES. 

becomes  less,  and  the  greenish  serpentinous  product  more  abundant,  until 
they  pass  into  a  greenish-gray  serpentinous  rock  spotted  with  secondary 
ferruginous  products.  In  many  of  the  intermediate  forms,  short,  brilliant 
crystals  of  actinolite  are  to  be  seen,  while  the  rock  assumes  a  more  or  less 
perfect  schistose  structure. 

In  the  microscopic  sections  the  series  passes  from  a  more  or  less  spongi- 
form  mass  of  magnetite,  holding  olivine  iind  more  or  less  feldspar,  into  forms 
that  show  in  portions  of  the  mass  an  alteration  to  a  greenish  serpentinous 
aggregate.  It  then  passes  into  a  form  destitute  of  the  feldspar,  in  which 
the  partially  altered  smoky  olivine  grains  are  surrounded  by  a  band  of 
secondary  actinolite,  while  the  greenish  serpentinous  product  increases  in 
abundance.  These  changes  go  on  with  diminishing  olivine  and  increasing 
actinolite  and  greenish  serpentinous  material,  until  they  have  entirely 
(especially  the  last)  replaced  the  olivine.  The  structure  remains  the  same, 
but  the  magnetite  sponge  is  more  discontinuous  and  in  part  dissolved,  while 
talc  appears.  In  others  dolomite  is  seen. 

In  some  sections  the  greenish  secondary  products,  with  little  or  no  actin- 
olite, replace  the  olivine.  The  figures  5,  6  (Plate  I.),  and  1,  2,  and  3  (Plate 
II.),  fairly  represent  the  general  structure  of  these  rocks,  and  their  resem- 
blance to  the  meteoric  pallasites. 

No  satisfactory  analyses  of  the  pallasites  exist  except  that  of  Professor  C. 
A.  Joy  of  an  Atacama  meteorite,  but  the  imperfect  ones  that  have  been 
found  have  been  tabulated,  so  as  to  give  a  rough  approximation  to  correct- 
ness. The  specific  gravity  determinations  are  also  not  satisfactory  as  a 
whole,  since  they  have  not  been  made  upon  characteristic  specimens,  but 
upon  selected  ones.  They  run  from  a  little  above  7  to  some  below  4,  but 
it  is  probable  that  the  majority  of  typical  pallasites  lie  between  4  and  6 ; 
although  we  must  expect  to  find  them  graduating  in  specific  gravity,  as  well 
as  in  other  characters,  into  both  the  siderolites  and  peridotites.  The  silica 
ranges  from  3  per  cent  up  to  33  per  cent,  but  the  probable  limits  are 
between  5  and  30  per  cent,  averaging  about  20  per  cent.  The  magnesia 
ranges  from  2  to  over  30  per  cent,  but  the  average  probably  will  be  found, 
by  correct  analyses,  to  lie  somewhere  between  10  and  20  per  cent.  The 
iron  in  various  conditions  is  a  variable  quantity,  but  averages  about  60  per 
cent ;  while  the  nickel,  with  one  exception,  is  less  than  10  per  cent.  In  the 
terrestrial  forms  (Cumberlandite)  nickel  is  wanting,  but  from  6  to  15  per 
cent  of  titanic  oxide  occurs.  Some  tin,  copper,  zinc,  cobalt,  phosphorus,  sul- 


I'ALLASITE.  —  CUMBERLANDITE.  83 

pluir,  chromium,  manganese,  lime,  and  aluminum  have  been  found  in  part  of 
the  specimens  analyzed.  More  and  accurate  analyses  are  needed  before  any- 
thing but  general  conjectural  statements  can  be  made.  If  the  analyses  of 
iron  ores  from  regions  of  crystalline  rocks  be  examined,  like  those  given  by 
Richard  Akcnnan  in  his  work  "  On  the  State  of  the  Iron  Manufacture  in 
Sweden,"  Stockholm,  1876,  also  from  Canada  and  elsewhere,  many  can  be 
found  whose  resemblance  to  those  of  Cumberlandite  is  so  close  as  to  warrant 
an  examination  of  the  structure  and  mode  of  occurrence  of  the  ore  analyzed. 
In  these  we  should  look  for  from  5  to  30  per  cent  of  silica  and  magnesia,  but 
not  of  necessity  for  any  titanium.  The  mere  analysis,  without  further  evi- 
dence, does  not  prove  the  relationship  —  it  merely  suggests  it. 


CHAPTER    III. 

THE   PEEIDOTITES. 

SECTION   I.  —  Introductory. 

THE  term  peridotite  is  employed  by  Professor  Rosenbusch  to  designate 
the  pre-Tertiary  terrestrial  rocks  that  are  composed  essentially  of  olivine, 
with  or  without  enstatite,  diallage,  angite,  magnetite,  chromite,  picotite, 
etc.*  The  writer  would  extend  it  so  as  to  include  all  terrestrial  and  extra- 
terrestrial rocks  of  similar  composition  and  structure,  and  all  the  derivatives 
of  both.  The  state  of  the  iron,  as  in  the  case  of  the  preceding  species,  does 
not  appear  to  him  to  be  a  sufficient  reason  for  separating  the  rocks  herein 
described  into  distinct  species.  The  descriptions  will  be  given  of  the  me- 
teoric peridotites  first,  and  of  the  terrestrial  ones  later,  as  a  matter  of 
convenience  only.  The  order  pursued  in  the  arrangement  of  the  meteoric 
peridotites  will  be,  so  far  as  possible,  the  same  as  that  followed  with  the 
terrestrial  ones,  —  those  composed  of  olivine  first,  or  the  dunite  variety ;  then 
those  containing  olivine  and  enstatite  (olivine-enstatite  rocks) ;  then  those 
containing  olivine,  enstatite,  and  diallage,  or  the  Iherzolite  variety;  etc. 
In  each  case  those  approaching  nearest  to  the  glassy  condition  will  be 
described  first.  Of  necessity  this  'scheme  has  many  imperfections,  owing 
to  the  limited  number  of  specimens  studied  microscopically. 

While  the  writer  does  not  believe  in  the  necessity  or  value  of  dividing 
the  peridotite  into  either  species  or  varieties  —  holding  that  they  are  all 
essentially  of  one  type,  whatever  may  be  the  especial  mineral  composition  — 
he  recognizes  the  fact  that,  excepting  himself,  lithologists,  universally,  do  so 
divide  these  rocks.  He  then  thinks  it  better  to  conform  for  the  present  to 
that  method,  so  far  as  seems  necessary  and  convenient  to  aid  the  science, 
and  not  to  retard  its  progress.  It  seems  necessary,  then,  in  deference  to  the 
prevailing  sentiment,  that  the  olivine-enstatite-bearing  rocks  should  be  sepa- 

«  Mikros.  Phys.  ii.  524-545. 


INTRODUCTORY.  85 

rated  as  a  variety,  the  same  as  the  olivine-enstatite-diallage  ones  have  been 
erected  into  the  variety  Iherzolite.  Believing,  as  he  does,  that  the  same 
methods,  rules,  and  principles  should  be  employed  in  studying  meteorites 
as  those  used  for  the  terrestrial  rocks,  and  that  both  classes  are  in  reality 
the  same,  it  follows  that  the  same  name  should  be  used  for  both,  and  the 
differences  expressed  adjectively  if  necessary. 

In  accordance  with  this,  the  variety  of  peridotite  distinguished  by  olivine 
should,  both  as  meteorites  and  terrestrial  rocks,  be  designated  by  the  term 
already  in  common  use  for  the  latter  —  dunite.  For  that  variety  which  con- 
tains olivine  and  enstatite,  the  German  term  enstatit-olivinfels  employed  by 
Dr.  Dathe  is  too  cumbersome  for  Anglo-Saxon  use,  or  even  for  any  general 
use.  It  is,  then,  proposed  here  to  designate  all  these  rocks  by  the  term 
saxonitc,  from  the  country  in  which  the  terrestrial  form  was  first  so  well 
described  by  Dathe. 

The  term  Iherzoliie  is  here  applied  to  those  rocks  characterized  by  ensta- 
tite, diallage,  and  olivine.  The  forms  that  are  characterized  by  the  presence 
of  olivine,  enstatite  (bronzite),  and  augite,  are  designated  by  the  term  buch- 
ncrite,  given  in  honor  of  Dr.  Otto  Buchner,  to  whose  writings  on  meteorites 
we  are  so  much  indebted,  and  who  gave  the  first  description  of  a  meteorite 
having  this  composition. 

The  term  eulysitc  is  employed  for  the  olivine-diallage  forms,  and  picrite  for 
the  olivine-augite  variety.  Of  course,  for  all  of  the  highly  altered  forms  for 
which  the  term  serpentine  has  been  already  used,  that  name  is  retained  ;  but 
in  many  cases,  when  it  is  known  from  what  special  variety  the  serpentine 
has  been  produced  by  alteration,  it  has  been  described  under  that  variety  in 
order  to  show  its  relations.  This  has  particularly  been  the  case  with  forms 
coining  from  the  same  rock  in  a  single  locality,  but  showing  different 
stages  of  alteration.  The  fragmental  forms,  of  which  only  a  few  have  been 
described,  are  classed  under  the  term  poroditc  *  for  the  old  and  altered  forms, 
and  tufa  for  the  unaltered.  Thus  far,  in  meteorites,  the  fragmental  rocks  are 
all  tufas,  and  in  the  terrestrial  peridotites,  porodites. 

»  Bull.  Mus.  Comp.  Zool.,  1879,  v-  280. 


86  PEHIDOT1TE. 

SECTION  II.  —  The  Meteoric  Peridotites. 

VARIETY.  —  Dimite. 

Chassigny,  France. 

The  meteorite  of  Chassigny  *  is,  according  to  Damour,  of  a  pale- yellow  tint.  Under  a 
lens  it  is  seen  to  be  formed  of  a  multitude  of  little  rounded  grains,  with  a  vitreous  lus- 
tre. In  these  grains  occur  some  of  a  deep-black  color.  This  description  is  identical 
with  that  which  could  be  given  of  an  unaltered  dunite,  like  that  from  Franklin,  N.  C., 
for  example. 

According  to  Tschermak,  microscopically,  this  meteorite  is  composed  of  a  pale  yellow- 
ish olivine,  traversed  by  fissures,  and  containing  brownish  glass  inclusions.  Between 
the  olivine  grains  there  are  to  be  seen  here  and  there  three-sided  cavities,  filled  with 
colorless  or  brownish  glass,  from  which  often  radiate  the  fissures  traversing  the  olivines. 
In  the  glass  can  be  seen  with  high  powers  colorless  grains,  needles,  and  brown  crystals. 
Octahedrons  of  chromite  occur  irregularly  scattered  through  the  rock.f 

VARIETY.  —  Saxonite. 

loiva  County,  Iowa. 

The  Iowa  County,  Iowa,  meteorite  in  the  Harvard  College  Cabinet  presents  a  fine- 
grained groundmass,  sprinkled  with  pyrrhotite  and  iron.  On  the  polished  surface  it 
shows  a  well-marked  chondritic  structure. 

This  meteorite  was  described  by  Prof.  C.  W.  Gtimbel,  in  1875,  as  composed  of  oli- 
vine, an  augitic  material,  iron,  troilite,  chromite,  reddish  garnet-like  inclusions,  etc.  He 
holds  that  the  rock  is  entirely  crystalline,  but  fragmental  in  character.  The  reader  is 
referred  to  the  original  paper  for  Gtimbers  figure  and  views,  f 

Specimens  of  this  meteorite  were  purchased  for  the  Whitney  Lithological  Collection 
of  the  Museum  of  Comparative  Zoology,  from  Ward  and  Howell.  Eochester.  N.  Y.,  and 
sections  made.  The  sections  are  colored  gray,  with  patches  of  brownish-yellow  staining 
from  the  iron.  The  gray  groundmass  contains  irregular  detached  bits  of  metallic  iron, 
about  which  the  stain  extends.  The  groundmass  is  composed  of  crystals  and  grains  of 
olivine,  enstatite,  pyrrhotite,  iron,  and  base.  The  section  shows  the  usual  chondritic 
structure,  in  which  granules  of  olivine  and  enstatite  are  cemented  by  the  base  to  form 
the  chondri.  I  can  find  neither  in  this  nor  in  any  other  meteorite  that  I  have  seen  any 
evidence  that  they  are  fragmental  in  character,  but  rather  evidence  that  the  structure 
usually  observed  is  the  result  of  rapid  cooling  upon  a  liquid  magma  of  this  constitution. 
The  crystalline  structure  of  any  mass  depends  upon  the  crystalline  form  its  minerals 
tend  to  assume,  under  the  conditions  to  which  they  were  exposed  during  that  crystalliza- 
tion. In  the  crystalline  forms  of  olivine  and  enstatite,  coupled  with  the  rapid  cooling, 

*  Comptes  Rendus,  1862,  Iv.  591. 

f  Sitz.  Wien.  Akad.,  1883,  Ixxxviii.  (1),  361,  362. 

J  Sitz.  Akad.  Miinclien,  1875,  v.  313-330. 


THE   METEORIC   PERIDOTITES.  —  SAXONITE.  87 

the  writer  believes,  resides  the  cause  of  the  peculiar  structure  of  the  chondritic  meteor- 
ites, while,  if  through  any  cause  the  mass  cools  more  slowly,  the  result  is  to  unite  the 
detached  grains  into  larger  crystals,  as  in  the  Estherville  meteorite  and  in  the  ordinary 
terrestrial  peridotites.  These  structures,  certainly,  do  not  vary  any  more  from  one 
another  than  do  the  glassy,  the  glassy  and  globulitic,  and  the  crystalline  forms  of  hasalt. 

The  base  in  this  peridotite  varies  from  a  light  to  a  dark  ash-gray,  and  is  fibrous-gran- 
ular  in  its  structure.  The  darker  shades  are  generally  associated  with  the  olivine  and 
the  lighter  with  the  enstatite.  Various  gradations  are  seen  between  that  state  of  the 
base  which  does  not  affect  polarized  light,  and  that  which  shows  feeble  coloration  — 
properly  not  a  base.  These  gradations  are  owing  to  the  differentiation  in  it  of  more  or 
less  granules  of  olivine  or  enstatite,  causing  the  depolarization  of  the  light.  The  feeble 
polarization  appears  to  be  owing  to  a  differentiation  of  the  base  so  as  to  leave  but  mi- 
nute, portions  of  it  in  the  original  state,  although  the  difference  between  the  two  states  is 
not  noticeable  in  common  light.  The  tendency  of  these  granules  is  to  unite  into  a  homo- 
geneous crystal,  the  base  disappearing  more  and  more,  according  to  the  conditions  attend- 
ing the  solidification  of  the  nuiss.  Furthermore,  as  in  other  rocks,  so  in  this,  the  base 
should  be  expected  to  be  one  of  the  first  materials,  after  the  iron,  to  suffer  alteration. 
The  writer  supposes  this  base  to  be  that  which  other  writers  have  described  as  the 
matrix  of  fine  dust,  formed  by  the  comminution  of  'the  meteoric  material,  —  flocculent, 
opaque,  white  mineral ;  *  also  as  felspathic  material,  etc. 

A  series  of  grains  and  crystals  of  olivine,  arranged  in  spherical  form  and  cemented 
by  the  fibrous-granular  base,  forms  the  olivine  chondri.  I  do  not  regard  these  as  rounded 
forms,  owing  their  shape  to  mechanical  action,  for  no  abrupt  line  separates  them  from 
the  surrounding  material,  as  is  the  C€ise  when  detached  fragments  are  inclosed  in  a 
matrix.  In  the  same  way  the  granules  themselves  show  that  they  are  products  of  crys- 
tallization, and  not  broken  fragments  held  in  the  matrix.  As  said  before,  I  can  see  no 
structure,  in  this  or  in  any  of  the  other  meteorites  examined,  supporting  the  mechanical 
theory  of  their  origin;  but  everything  observed,  in  my  judgment,  points  to  crystalliza- 
tion in  a  more  or  less  rapidly  cooling  body.  In  some  instances  it  is,  indeed,  true  that  an 
abrupt  termination  exists  to  some  of  the  forms,  but  these  appear  to  be  fragments  of 
base,  sometimes  partly  differentiated,  caught  in  the  liquid  mass,  instead  of  mechanical 
forms  torn  from  some  previously  existing  rock. 

This  meteorite  has  also  been  described  by  Lasaulx,  who  states  that  it  shows  an  evi- 
dent brecciated  structure,  with  olivine  grains  and  rounded  enstatite  masses,  in  a  fine- 
grained groundmass,  containing  grains  and  fragments  of  crystals,  as  well  as  iron  and 
pyrrhotite.  Plagioclase  is  said  to  be  present,  and  the  base  is  described  as  a  gray,  fine- 
grained, aggregate,  cementing  mass,  resembling  the  granular  microfelsitic  groundmass 
of  many  porphyries.! 

Figure  4,  Plate  II.,  shows  well  the  finer-grained  portions  of  this  meteorite  with 
the  native  iron.  The  portion  to  the  left  of  the  centre  represents  one  of  the  chondri, 
composed  of  detached  grains  held  in  a  dark  base.  The  grains  are  found  to  be  divided  by 
polarized  light  into  three  sets,  one  of  which  occupies  the  lower  portion  and  the  other  two 
the  upper  portion  of  the  chondrus.  The  grains  in  each  division  act  optically  as  a  unit, 
and  cause  the  choudrus  to  present  the  appearance  of  a  crystal  composed  of  three 
twinned  portions ;  and  it  is  here  thought  that  had  not  the  crystallization  been  arrested, 

»  Mnskelyne,  Phil.  Mag ,  1863  (<t),  xxvi.  138. 
t  S:tz.  nicdcr.  Gcsclls.  15ouu,  18S2,  pp.  102-105. 


88  PERIDOTITE. 

the  grains  would  have  united  from  the  crystallization  of  the  base,  and  a  three-twinned 
rounded  crystal  resulted.  The  remaining  portion  of  the  figure  is  composed  of  base, 
olivine,  enstatite,  chondri,  iron,  pyrrhotite,  and,  possibly,  magnetite. 

Figure  5,  on  the  same  plate,  shows  one  of  the  large  chondri  composed  of  olivine  and 
enstatite,  which  blends  at  the  lower  portion  of  the  figure  with  the  general  groundmass, 
showing  that  they  are  only  somewhat  differently  differentiated  portions  of  the  con- 
tinuous mass.  The  grains  are  surrounded  by  a  gray  base,  while  the  yellowish  and  red- 
dish-brown tints  represent  the  staining  from  the  oxidation  of  the  iron.  In  figure  4  the 
base  is  darker  than  represented,  and  in  figure  5  lighter.  The  colors  of  the  two  should  be 
exchanged. 

Dhurmsala,  Punjab,  India. 

This  meteorite  is  described  by  Professor  A.  von  Lasaulx  as  having  a  light-gray 
groundmass,  sprinkled  with  yellowish  rusty  spots.  Microscopically,  it  was  seen  to 
possess  a  chondritic  structure,  similar  to  the  meteorite  from  Iowa  County.  The  chon- 
dri are  composed  of  olivine  and  enstatite,  with  the  fibrous  cementing  material.  Besides 
olivine  and  eustatite  the  rock  contains  iron  and  troilite,  as  well  as  chromite  or  mag- 
netite.* 

Knyakinya,  Hungary. 

The  Knyahinya  meteorite  was  examined  microscopically  by  Professor  Adolf  Kenn- 
gott  in  1869.  His  section  was  of  a  gray  color  spotted  with  yellow,  semi-transparent,  but 
containing  opaque  and  dark-yellow  spots.  The  whole  appears  finely  grained  to  the 
unaided  vision,  but  spheroidally  grained  under  a  low  magnifying  power.  The  granules 
are  gray,  and  some  of  them  more  or  less  angular.  Besides  the  metallic  and  opaque  par- 
ticles two  crystalline  minerals  were  seen.  One  is  colorless  and  transparent,  the  other 
gray  and  translucent.  Some  of  the  spherules  consist  essentially  of  one  or  the  other  of 
these  minerals.  The  opaque  substances  are  subordinate,  and  are  interposed  between  the 
rounded  or  angular  granules.  Kenngott  regards  this  spherulitic  structure  as  the  result  of 
a  process  of  crystallization  within  the  substance  of  the  meteorite,  and  not  from  an  aggre- 
gation of  separately  formed  bodies. 

The  opaque  substances  are  light-gray  metallic  iron,  grayish-yellow  pyrrhotite,  and  a 
black  material.  In  reflected  light  the  iron  appears  dark -gray  and  translucent,  the  pyr- 
rhotite blackish-yellow  and  faintly  diaphanous,  and  the  black  substance  opaque.  The 
silicates  are  regarded  as  enstatite  and  olivine. 

Descriptions  of  the  granules  (chondri)  were  given  by  Professor  Kenngott.  One  is 
said  to  possess  a  striped  appearance,  owing  to  alternations  of  a  delicate  transparent  sub- 
stance with  a  gray  one.  The  bands  are  partly  parallel  and  partly  divergent.  When 
the  power  is  900  the  structure  is  resolved  into  a  mere  aggregation  of  gray  and  hyaline 
particles.  The  gray  mineral  (enstatite)  constitutes  essentially  many  of  the  round  or 
rounded  granules,  while  other  granules  are  formed  from  a  union  of  the  olivine  and 
enstatite.  The  two  silicates  crystallized  simultaneously,  one  or  the  other  of  them,  accord- 
ing to  circumstances,  having  accumulated  around  certain  centres  in  a  spherical  form,  thus 
imparting  to  the  meteorite  as  a  whole  a  somewhat  oolitic  aspect.  The  original  paper  is 
illustrated  by  drawings  of  the  granules.! 

*  Sitz.  niedcr.  Gesells.  Bonn,  1882,  pp.  105-107. 

f  Sitz.  Wien.  Akad.,  1869,  lix.  (2),  873-SSO  ;  Phil.  Ma-.,  1869  (4),  xxxviii.  424-428. 


Till:    MKTF.ollIC    PER1DOTITES.—  SAXONITE.  89 

Later,  Dr.  Otto  Halm  thought  he  had  discovered  in  this  meteorite  a  plant  form  com- 
posed of  olivine.  This  plant  he  named  Urania  Guilidmi.  It  was  regarded  as  lying 
between  iilua-  and  ferns.*  Since  Halm  found  his  plants  in  granite,  gneiss,  serpentine, 
basalt,  and  meteorites,  even  in  the  metallic  nickel-iron  from  Toluca,  and  in  that  of  the 
Pallas  meteorite,  the  conclusion  would  follow  that  he  would  be  able  to  find  them  almost 
anywhere.  His  language  is  such  that  it  is  difficult  to  believe  that  his  paper  is  a  sober 
production,  and  not  a  parody  on  the  Eozoiin  literature,  especially  since  he  claims  to  have 
found  Kct/ndii  structure  in  the  Pallas  meteorite.  Perhaps  this  is  not  so  remarkable,  since 
Carpenter  found  the  same  in  graphic  granite,  f 

Whatever  may  have  been  Hahn's  design  in  the  publication  of  "Die  Urzelle,"  he  was 
evideiiUy  in  earnest  in  his  ''Die  Meteorite  (Choudrite)  und  ihre  Orgauismeu,"  Tubingen, 
1880. 

This  work  is  devoted  chiefly  to  the  structure  of  the  chondri  observed  in  the  Knya- 
liinyn  meteorite,  and  it  gives  very  fair  photographs  of  these.  Halm  believed  the 
chondri  were  sponges,  corals,  crmoids,  etc.,  while  Urania  was  in  this  book  placed  under 
the  sponges. 

There  are  some  things  which  pass  discussion,  and  Hahn's  works  belong  to  that  class ; 
for  the  kingdom  to  which  such  forms  belong  must  be  largely  a  question  of  belief  rather 
than  of  decisive  evidence.  The  artificial  formation  by  Meunier,  of  Hahn's  sponges,  corals, 
and  crinoids  in  a  red-hot  porcelain  tube  is  perhaps  the  most  decisive  fact  against  their 
organic  origin.  J 

The  writer  believes  that  this  is  one  of  the  very  common  cases  in  which  mineral  forms 
have  been  taken  to  be  organic  ones,  especially  by  those  who  were  familiar  with  the  latter 
and  not  with  the  former,  —  cases  to  some  of  which  attention  has  been  called  in  the 
"Azoic  System."  § 

Later,  Dr.  D.  F.  Weinland  continued  the  discovery  of  organic  forms,  principally  in 
the  Kuyaliinya  meteorite.  He  gives  but  two  figures  ;  that  of  Pcdiscus  ZMelii  is  appa- 
rently an  enstatite  crystal,  and  that  of  "  Huhnia  mdcoritica,  a  coral ! "  is  evidently  a  series 
of  olivine  grains.  || 

These  and  other  such  forms  can  be  found  in  all  chondritic  meteorites,  while  almost 
every  rock,  especially  if  altered,  will  afford  structures  that  can  be  tortured  into  organic 
forms,  if  the  imagination  or  desire  be  strong  enough.  After  this  has  been  done,  who 
shall  say  that  the  authors  were  not  correct  ?  Is  not  the  case  similar  to  that  of  the 
I,  \nijn  Canadensc  —  dependent  solely  on  weight  of  authority  ?  Yet  the  Eozoon  occurs  in 
rocks  proved  to  be  veinstones  ! 

The  specimen  of  the  Knyahinya  meteorite  in  the  Whitney  Collection  shows  on  the 
fracture  a  gray  color  and  a  chondritic  structure. 

ion  :  The  sections  show  a  gray  chondritic  mass,  marked  in  places  by  a  yellowish- 
brown  ferruginous  staining  ;  and  they  are  seen  under  the  microscope  to  be  composed  of  a 
crystalline  granular  and  chondritic  mass,  the  parts  often  held  by  the  dark-gray  and  light- 
gray  fibrous  base  and  semi-base.  The  chondri  in  these  sections  are  seen  to  be  composed 

»  See  Die  Urzclle,  Tubingen,  1879,  pp.  54-56,  and  Plate  XVII. 

f  Nature,  1S76,  xiv.  8,  9,  68. 

t  Comptes  Rendus,  1SS1,  xeiii.  737-739  ;  Am.  Jour.  Sci.,  18S2  (3),  xxiii.  155,  156. 

§  Bull.  Mus.  Comp.  Zool.,  1884,  vii.  No.  11. 

||  Uebcr  die  in  Mrlmrilen  eutdecku-ii  Thierreste.  Esslingpn,  1882.  See  also  Die  liypnlhetischen  Orgaii- 
iMiirii-Krstc-  in  M,  |: -Mi-It, -n,  von  Dr.  F.  Kullc,  Wiesbaden,  1884 ;  and  Les  Pre'tcndus  Organismes  dcs  Mete- 
orites, par  C'.irl  YMJ-I.  <;,  ni-ve,  1882. 

12 


90  PEHIDOTITE. 

of  enstatite,  olivine,  enstatite  and  base,  olivine  and  base,  enstatite  and  olivine,  and  of  base 
and  minute  granules  of  either  olivine  and  enstatite. 

One  of  the  chondri  is  seen  to  possess  an  approximately  square  centre  of  enstatite 
with  some  projecting  points.  Surrounding  this,  and  also  partially  held  in  it,  is  the  gray 
base  and  semi-base,  showing  over  much  of  its  surface  a  feeble  polarization,  which  extin- 
guishes at  the  same  time  with  the  enstatite.  The  latter  shows  traces  of  zone  building, 
and  lying  parallel  to  the  sides  are  other  small  masses  of  enstatite,  which  appear  to  form 
constituent  portions  of  the  enstatite  crystal.  In  polarized  light,  the  entire  chondrus 
appears  as  a  homogeneous  enstatite,  except  that  certain  portions  show  more  feeble  colora- 
tion. The  structure  seems  to  me  to  be  that  of  a  mineral  crystallizing  out  of  a  magma,  the 
processes  being  arrested  before  it  was  complete.  Another  chondrus  shows  a  bouf|iiet-like 
mass  of  the  fibrous  gray  matter  in  the  centre,  surrounded  in  part  by  long  masses  of 
enstatite,  which  hold  included  between  and  in  them  portions  of  the  base.  This  is  figured 
in  Plate  II.  figure  6,  at  the  centre  and  on  right  of  the  central  portion  of  the  figure.  The 
lighter  bars  surrounding  and  cutting  the  yellowish-gray  fibrous  portion  are  enstatite, 
which  polarize  conjointly  as  a  single  crystal.  They  contain  portions  of  the  base  forming 
the  grayish  parts.  The  central  fan-shaped  portion  is  composed  of  base  mixed  with 
enstatite  fibres  and  iron  grains,  and  stained  by  oxide  of  iron.  At  the  bottom  of  the 
figure  is  another  chondrus  composed  of  mixed  enstatite  fibres  and  base,  while  towards 
the  left  and  bottom  of  the  figure  is  a  fissured  enstatite.  The  rest  of  the  figure  is  com- 
posed of  enstatite,  olivine,  and  base,  showing  in  places  imperfect  chondritic  structure. 

In  another,  the  fan-like  radiation  of  the  base  with  the  enstatite  granules  begins  at 
opposite  ends  of  the  chondri,  meeting  and  interlocking  towards  the  middle,  but  leaving 
a  non-differentiated  oblong  nebulous  mass  in  the  centre  between  them.  The  two  por- 
tions interlock  in  such  a  manner  that  they  evidently  form  the  same  crystal  mass  —  the 
rudiments  of  a  twinned  crystal. 

Some  chondri  are  composed  of  a  rude  network  of  base — the  meshes  being  filled 
with  olivine  grains.  This  is  shown  in  Kenngott's  figure  8.  One  chondrus  is  composed 
of  an  enst<itite  crystal  surrounded  by  a  narrow  border  of  gray  matter,  apparently  crowded 
out  by  the  crystallization  of  the  enstatite,  as  is  often  the  case  iii  the  crystallization  of  the 
feldspars  in  modern  lavas. 

Chondri  are  seen  composed  entirely  of  olivine  grams,  the  lines  bounding  the  grains 
answering  to  the  network  of  base  before  mentioned.  One  formed  by  an  enstatite 
mass  with  black  ferruginous  grains  (magnetite)  is  found  to  continue  across  its  apparent 
boundary  into  the  adjoining  enstatite,  the  cleavage  fractures  and  fissures  extending  from 
one  to  the  other,  both  forming  in  common  and  polarized  light  a  continuous  enstatite 
crystal. 

Another  chondrus  is  composed  of  a  sea-fan-like  interior  made  up  of  base  and  fine 
granules  of  olivine  (?)  surrounded  by  a  coarser  granular  mass  destitute  of  base,  the  entire 
chondrus  showing  in  common  and  polarized  light  that  it  was  a  homogeneous  mass,  out  of 
which  the  granules  have  crystallized. 

In  others,  the  base  is  irregularly  scattered  through  the  crystals,  and  held  as  the  base 
is  in  minerals  in  recent  lavas.  The  base  in  this  meteorite  is  often  completely  dark 
during  the  entire  revolution  of  the  stage,  and  every  gradation  exists  between  this  state 
and  that  in  which  it  affects  the  polarized  light  considerably  —  nearly  crystallized  into 
the  enstatite  and  olivine  forms.  While  the  color  of  the  base  is  usually  a  gray,  in  some 
cases  it  is  of  a  brown  to  a  black  color  in  transmitted  light.  The  descriptions  of  the 
chondri  might  be  greatly  extended,  but  it  would  seem  that  enough  has  been  given  to 


THE  METEORIC   PERIDOTITES.—  SAXONITE.  91 

show  that  the  olivine  and  enstatite  crystallize  out  of  the  base,  and  that  in  the  state  of 
incipient  crystallization  these  minerals,  coupled  with  the  base,  assume  the  forms  that 
have  been  taken  for  organic  ones.  The  irregular  distribution  and  relations  of  the  base  to 
the  crystal  grains  show  that  even  apparent  organic  forms  tire  wanting  except  in  selected 
cases.  The  mineral  constitution  of  the  meteorite  is  such  that  it  could  not  have  been 
exposed  to  air  and  water  without  alteration  of  the  minerals,  but  must  have  been  formed 
under  such  conditions  that  those  agencies  could  not  have  produced  their  customary 
effects,  i.c.,  under  the  action  of  heat.  Action  that  was  sufficient  to  crystallize  enstatite 
and  olivine  out  of  a  fossiliferous  deposit,  surely  would  have  been  sufficient  to  obliterate 
every  trace  of  such  delicate  microscopic  organisms  as  these  supposed  corals  and  crinoids. 
If  these  forms  were  organic,  then,  as  Professor  J.  Lawrence  Smith  has  justly  observed, 
carbonate  of  lime  ought  to  be  found  in  them,  which  is  not  the  case.  The  entire  mass  of 
the  meteorite  is  made  up  of  enstatite,  olivine,  iron,  base,  pyrrhotite,  and  apparently  a 
magnetite. 

Its  chondri  appear,  with  possibly  a  few  exceptions,  to  be  secretions  in  the  mass 
formed  by  the  tendency  to  crystallization,  as  was  pointed  out  in  the  case  of  the  preceding 
meteorite,  since  they  pass  as  a  continuous  mass  into  the  surrounding  material,  and  have 
not  the  well-defined  boundaries  of  a  foreign  or  included  mass.  The  possible  exceptions 
are  of  a  few  forms  that  appear  as  if,  while  in  a  liquid  or  plastic  state,  they  might  have 
been  inclosed  in  a  liquid  or  plastic  mass,  and  partly  united  with  it.  The  supposed  frag- 
mental  portions,  or  the  grains,  appear  to  me  to  be  formed  by  crystallization,  the  same  as 
the  grains  are  formed  in  common  peridotic  rocks,  and  not  by  attrition.  Some  of  the 
chondri  are  deformed  by  others,  as  would  be  natural  in  such  a  crystallizing  mass. 


Gnadcnfrci,  Silesia. 

This  meteorite  has  been  described  by  Professors  J.  G.  Galle  and  A.  von  Lasanlx  as 
having  a  chondritic  structure.  The  grouudmass  is  colored  light-gray,  and  contains 
numerous  spherules,  colored  white,  gray,  or  dark-gray.  Particles  of  iron  of  varying  size 
occur,  while  under  the  lens  there  are  clearly  seen  little  granular  particles  of  bronze- 
colored  pyrrhotite  and  brass-yellow  spangles  of  troilite.  Rusty-brown  spots  occur,  aris- 
ing from  the  rapid  oxidation  of  the  iron. 

Under  the  microscope,  the  thin  sections  were  found  to  contain  nickeliferous  iron, 
pyrrhotite,  troilite,  chromite,  enstatite,  and  olivine.  The  iron  is  in  irregular  pronged 
masses. 

Our  authors  separate  the  troilite  from  pyrrhotite,  the  former  being  rare  in  little 
yellowish  grains,  and  the  latter  more  abundant,  in  small  granular  aggregates  having  a 
bronze  color,  also  in  little  grains  in  the  silicates  and  in  the  iron.  The  chromite  is  in 
small  octahedrons  in  the  olivine.  The  enstatite  appears  both  in  the  groundmass  and  in 
the  spherules.  It  contains  inclusions  of  brown  and  colorless  glass  with  fixed  bubbles, 
and  black  metallic  particles;  also  a  black  dust-b'ke  substance.  All  the  inclusions  are 
more  or  less  elongated  in  the  direction  of  the  cleavage  lines. 

The  olivine  occurs  both  in  the  groundmass  and  in  the  spherules.  It  is  in  rounded 
grains  or  crystal  fragments  of  irregular  contour.  The  grains  are  colorless  except  when 
discolored  by  the  oxidation  of  the  metallic  iron.  The  olivine  contains  brown  glass 
inclusions  with  one  or  two  bubbles,  also  a  black  dust-like  substance,  the  same  as  that 
inclosed  in  the  enstatite. 


92  PERIDOTITE. 

The  chondri  are  composed  principally  of  olivine  and  enstatite,  and  show  the  usual 
variations ;  but  for  the  descriptions  the  reader  is  referred  to  the  original  paper.* 

Gopalpur,  India. 

The  Gopalpur  meteorite  was  microscopically  studied  by  Tschermak.  Its  color  is 
grayish-brown,  but  in  the  interior  whitish-gray.  The  groundmass  is  filled  with  numer- 
ous little  spherules,  which  are  of  a  brownish-gray  or  a  clear  gray  color.  Throughout,  the 
groundmass  glitters  with  yellowish  points  of  pyrrhotite.  Cellular,  pronged  grains  of  iron 
could  be  seen  in  the  section. 

This  meteorite  belongs  to  the  chondrites  of  Eose.  The  whitish  groundmass  is 
earthy,  tufaceous,  containing  angular  fragments  of  anisotropic  minerals  of  various  sizes. 
The  larger  fragments  show  a  fibrous  or  stalk-like  structure  with  an  evident  cleavage 
parallel  to  their  longer  direction ;  or  they  are  traversed  only  by  irregular  fissures.  The 
groundmass  con  tarns  particles  of  pyrrhotite  and  iron  of  various  sizes.  Immediately 
about  the  iron  is  to  be  seen  a  small  amount  of  a  dust-like,  untransparent,  dark-brown 
material  which  Tschermak  regards  as  chromite. 

The  larger  spherules  are  composed  principally  of  a  radiating  fibrous  mineral,  which  is 
taken  to  be  bronzite  (enstatite).  Sometimes  a  granular  mineral  was  observed  in  them. 
Other  spherules  are  made  up  of  irregular  fissured  grains  which  are  referred  to  olivine ; 
and  still  others  are  thought  to  be  composed  of  feldspar.  From  the  figures  and  descrip- 
tions given,  the  present  writer  thinks  that  the  presence  of  feldspar  is  doubtful,  although 
Tschermak  is  one  of  the  best  authorities  on  that  point.  The  author  hopes  that  a  careful 
re-examination  of  the  sections  will  be  made. 

The  large,  dark,  opaque  particles  in  the  spherules  and  groundmass  are  iron  and 
pyrrhotite. 

The  spherules  are  said  not  to  be  different  in  composition  from  the  groundmass.  In 
both  can  be  recognized,  as  the  essential  constituents,  bronzite  (enstatite),  olivine,  iron,  and 
pyrrhotite.  The  only  difference  is  that  in  the  spherules  the  crystal  grains  are  smaller. 

Tschermak  holds  that  the  chondritic  structure  displayed  in  this  meteorite  was  the 
result  of  a  mutual  attrition  of  the  differeut  particles,  the  whole  afterwards  being  cemented 
together.  He  regards  the  whole  structure  as  different  from  any  terrestrial  structure  yet 
observed,  f 

But  sura,  India. 

The  Butsura  meteorite  was  described  by  Professor  N.  S.  Maskelyne  in  1863,  as  having 
a  yellowish-brown  groundmass  containing  numerous  points  of  metallic  iron.  Irregular 
dark  stains  were  observed  surrounding  the  iron.  The  iron  is  very  evenly  distributed  in 
small,  isolated,  irregularly  formed  and  sometimes  crystalline  looking  particles.  Under 
the  microscope  the  chief  mass  of  the  meteorite  was  regarded  as  olivine,  associated  with 
a  gray  and  an  opaque  white  mineral.  The  gray  mineral  constitutes  entire  nodules  in 
the  meteorite,  and  sometimes  seems  mingled  in  the  apparently  brecciated  mass,  con- 
taining olivine  crystals  that  form  other  nodules  in  it.  It  presents  the  appearance  in  the 
former  case  either  of  a  dark  mottled  surface  spangled  with  dark  points,  or  of  a  mineral 
presenting  very  regular  and  minute  parallel  cleavage-planes,  with  dark-gray  bars  running 

*  Mon.  Berlin  Akad.,  1879,  pp.  750-771. 

f  Sitz.  Wien.  Akad.,  1872,  Ixv.  (1),  135-110;  Min.  Mitth.,  1872,  pp.  95-100. 


THE   METEORIC   PERIDOTITES.  —  SAXONITE.  93 

along  them,  often  in  divergent  rays.  Another  mineral  was  observed  which  was  trans- 
parent ami  pre.M'iitcd  cleavages  nearly  perpendicular  to  each  other.  The  specific  gravity 
of  this  meteorite  is  3.60.* 

From  the  above  description  it  is  inferred  that  tliis  peridotite  is  composed  principally 
of  olivine  and  enstatite. 

LancS,  Loir-el-Cher,  France. 

The  Lanc6  meteorite  was  examined  microscopically  by  Dr.  Richard  v.  Drasche.  It 
belongs  tn  the  chondritic  type  of  Rose,  and  in  the  thin  section  showed  a  confused 
jjroiindmass  holding  a  great  number  of  rounded  forms  of  varying  structure,  together  with 
isolated  crystal  fragments.  The  spherules  were  found  to  be  composed  either  of  olivine  or 
of  bronzite  (enstatite).  Iron  and  pyrrhotite  also  were  seen. 

Ihasehe  sums  up  the  structure  of  the  rock  as  follows:  The  meteorite  is  formed  by 
many  isolated  oliviue  crystals,  and  here  and  there  a  bronzite,  together  with  a  large 
numljer  of  spherules  of  two  different  kinds,  lying  in  a  tufaceous  powder.  The  spherules 
are  either  ivgularly  or  irregularly  arranged  aggregates  of  olivine,  or  they  are  formed  of 
liiouzite  needles  radiating  eccentrically.  Plates  with  a  full  description  of  the  meteorite 
were  given  by  Drasche.f 

Tourinnes-la-  Grossc,  Belgium. 

The  Tourinnes  meteorite  was  studied  microscopically  by  the  Rev.  A.  Renard,  S.  J. 

He  found  that  upon  the  fractured  surface  the  rock  was  of  a  grayish-white  color,  fine- 
granular  in  structure,  and  with  but  little  coherence. 

Under  a  lens  small  spherules  of  a  grayish-brown  or  a  pale-gray  color  were  seen,  also 
yellowish  points  of  pyrrhotite.  This  meteorite  belongs  to  the  chondritic  type  of  Rose. 

Under  the  microscope  the  grouudmass  is  found  to  have  but  little  coherence,  and  to  be 
formed  by  an  agglomeration  of  particles,  the  chief  of  these  being  non-cemented  grains  of 
olivine  of  irregular  contour.  Porphyritically  inclosed  in  this  granular  groundmass  were 
observed  iron,  pyrrhotite  (troilite),  enstatite,  and  olivine. 

The  nickeliferous  iron  is  in  the  form  of  indented,  cellular  grains.  The  enstatite  is 
gray  or  colorless,  and  possesses  a  fibrous  structure. 

The  olivine  shows  the  same  characters  as  it  does  in  the  terrestrial  peridotic  rocks.  It 
does  not  appear  that  the  irregularity  of  the  grains  was  necessarily  due  to  mechanical 
action,  since  the  same  structure  is  to  be  seen  in  the  terrestrial  peridotic  rocks,  as  for 
instance  that  from  the  St.  Paul's  Rocks. 

The  chondri  were  separated  into  two  groups :  those  formed  from  prisms  and  fibres 
of  enstatite,  and  those  formed  from  an  agglomeration  of  olivine  granules. 

1J>  nard  held  that  the  chondritic  structure  was  different  from  any  terrestrial  form,  and 
that  it  was  produced  through  the  projection  of  incoherent  volcanic  matter,  which  through 
its  agglomeration  formed  the  tufaceous-like  meteorites.  J 

Waconda,  Milchel  Co.,  Kansas. 

Some  description  of  this  meteorite  has  been  given  by  C.  U.  Shepard  and  J.  L.  Smith.§ 
According  to  the  latter  it  is  composed  of   iron,   pyrrhotite  (troilite),  olivine,  and 

•  Phil.  Mag.,  1SC3  (-1),  xxv.  50-58.  f  Mm.  Mittli.,  1873,  pp.  1-8. 

J  Mem.  Soc.  Beige  Micros.,  1879,  v.  43-50. 

§  Am.  Jour.  Sci.,  1876  (3),  xi.  473,  474;  1877,  xiii.  211-213. 


94  PEEIDOTITE. 

pyroxene  minerals.  The  specimens  purchased  for  the  Whitney  Collection  from  Ward 
and  Howell  show  an  ash-gray  groundmass,  stained  with  brownish  spots  of  rust,  and  con- 
taining grains  of  grayish-brown  olivine. 

Section :  a  yellowish-brown  and  grayish  groundmass  containing  iron.  On  one  side  a 
black  band  forming  the  exterior  (rind)  of  the  meteorite  is  preserved.  The  groundmass 
is  composed  of  olivine  grains  with  some  enstatite.  The  yellowish-brown  color  is  owing 
to  a  ferruginous  staining  of  the  silicates,  while  the  rind  is  composed  of  the  same  minerals 
as  the  interior,  but  owing  to  the  heat  to  which  it  has  been  exposed  it  has  been  burned 
black.  Clear  grains  of  untouched  silicates  (olivine  and  enstatite)  are  to  be  seen  both  in 
the  interior  and  in  the  crust. 

lu  one  corner  of  the  section  a  small  amount  of  a  fine  ash-gray  semi-base  was 
observed  cementing  olivine  grains. 

The  mixed  enstatite  and  augite  with  iron,  and  a  ferruginous  stained  groundmass  are 
shown  in  figure  4,  Plate  III. 

Goalpara,  India. 

The  Goalpara  meteorite,  according  to  Tschermak,  is  a  dark-gray  granular  rock,  having 
a  porphyritic  structure.  In  the  deep-gray  groundmass  are  inclosed  clear  colorless  and 
yellowish  grains. 

On  microscopic  examination  the  meteorite  was  found  to  be  composed  of  enstatite, 
olivine,  iron,  and  pyrrhotite. 

The  enstatite  shows  well-marked  cleavage-planes  running  in  two  directions,  forming 
an  angle  of  92°  with  each  other.  The  olivine  has  no  cleavage,  and  does  not  occur  in 
distinct  crystals,  but  in  minute  grains  united  together.  The  groundmass  in  which  the 
olivine  and  enstatite  are  inclosed  is  very  fine-grained.  Microscopically  it  is  seen  to  be 
composed  of  minute  transparent  grains,  apparently  oliviue,  and  untransparent  forms. 
These  last  are  of  three  different  kinds :  iron,  pyrrhotite,  and  coal-like  bodies.  The  iron 
forms  a  sponge-like  mass,  with  extremely  thin  cell-walls  composed  of  cubic  crystals.  The 
coal-like  bodies  are  described  as  being  in  all  their  properties  similar  to  soot  (graphite?). 
The  groundmass  is  said  to  appear  in  branching,  leaf-like,  thread-like,  and  dot-like  forms, 
winding  between  and  around  the  grains  forming  the  olivine  clusters. 

The  student  is  referred  to  Tschermak's  paper  for  the  complete  description  and  figures 
illustrating  the  microscopic  structure.* 


VARIETY.  —  Lherzolite. 

Pultiisk,  Poland. 

The  Pultusk  meteorite  on  the  fresh  fracture  shows,  according  to  Werther,  as  a  light- 
gray  rock,  part  very  fine-grained,  and  part  of  a  somewhat  coarser  texture.  This  is 
interspersed  with  numerous  white  and  yellowish  points,  showing  metallic  lustre,  also 
brownish-yellow  spots  in  the  groundmass.  He  regards  the  rock  as  composed  of  nickel- 
iron,  olivine,  enstatite  (?),  and  chromite.f 

This  meteorite  was  further  described  by  Dr.  G.  vom  Eath  as  composed  of  a  fine 

*  Sitz.  Wien.  Akad.,  1S7Q,  Ixii.  (2),  855-865. 
f  Sehriften,  Kongsberg  Gesell.,  1S6S,  ix.  35-40. 


THE   METEORIC   PERIDOTITES.  —  LHERZOLITE.  95 

granular  to  compact  groundmass,  containing  nickel-iron,  pyrrhotite,  spherules,  olivine, 
\vhite  crystal  grains,  and  chromite.  He  states  that  the  nickel-iron  occurs  in  three  differ- 
ent forms :  in  large  grains,  in  laminae,  and  in  ramifying,  pronged  grains  sprinkled  through 
the  groundmass.  The  surrounding  groundmass  is  sometimes  stained,  through  the  altera- 
tion of  the  iron,  to  a  brown  color. 

The  pyrrhotite  occurs  in  small  irregular  grains  and  granules  of  a  tombac-brown  color, 
which,  through  a  slight  alteration,  change  to  a  dark  steel-gray. 

The  chromite  is  in  very  small  black  non-magnetic  grains,  and  only  in  minute 
amounts.* 

The  specimen  purchased  from  Ward  and  Ho  well  for  the  Whitney  Collection  has  an 
ash-^ray  color  and  shows  a  chondritic  structure.  It  contains  pyrrhotite  and  iron. 

Section :  composed  of  a  light-gray  chondritic  mass,  containing  grains  of  iron  and 
pvrrlmtite.  The  groundmass  is  composed  of  olivine,  enstatite,  and  some  diallage.  The 
chondri  are  formed,  in  part,  of  grains  and  crystals  of  olivine  and  of  enstatite,  cemented 
by  a  gray,  fibrous  base.  Like  those  examined  by  the  writer  in  other  meteorites  he  regards 
these  as  the  product  of  an  arrested  crystallization  in  a  rapidly  cooling  mass  —  the 
solidification  taking  place  before  crystallization  was  complete.  Part  of  the  enstatite 
chondri  do  not  show  the  usual  eccentric  structure,  but  a  parallel,  or  sometimes  a  very 
irregular  one. 

The  arrangement  of  the  pyrrhotite  and  iron  about  some  of  the  chondri  reminds  one 
of  the  similar  arrangement  of  the  rejected  or  "  pushed  out "  material  about  the  feldspars 
in  some  andesites. 

The  iron  is  in  part  outside  of,  and  in  part  entirely  surrounded  by,  the  pyrrhotite. 

Figure  1,  Plate  III.,  shows  a  large  chondrus  at  the  base  of  the  figure,  composed  of 
enstatitic,  aggregately  polarizing,  fibrous  material  The  form  shows  the  rounded  indenta- 
tions seen  by  Tschermak  in  the  Tieschitz  meteorite,  and  at  its  upper  portion  blends  with 
the  groundmass,  although  distinct  from  it  elsewhere.  Under  the  microscope  its  boun- 
daries appear  to  be  those  of  a  crystallizing  mass  and  not  those  of  a  foreign  inclusion  in 
the  groundmass.  At  the  left  of  this  chondrus  is  another  radiating  fibrous  one,  com- 
posed of  enstatite  ribs  cemented  by  connective  tissue  of  gray  base,  holding  metallic  iron 
grains.  The  remaining  portions  of  the  figure  are  composed  of  mixed  choudri  and  the 
constituents  of  the  rock. 

Figure  2,  Plate  III.,  shows  the  structure  of  a  chondrus  composed  of  olivine,  enstatite, 
iron,  base,  etc.,  with  its  blending  at  the  bottom  of  the  figure  into  the  groundmass. 

Figure  3,  Plate  III.,  shows  the  relations  of  a  mass  of  pyrrhotite  (troilite)  to  an 
inclosed  mass  of  metallic  iron,  and  the  whole  surrounded  by  the  chondritic  groundmass. 

New  Concord,  Guernsey  Co.,  Ohio. 

"A  crystalline  granular  rock  containing  pyrrhotite  and  iron,  and  showing  yellowish- 
brown  spots  of  staining  arcuml  the  latter. 

Section :  a  light-gray  crystalline  mass  of  olivine,  pyroxene  and  enstatite,  and  con- 
taining iron  and  pyrrhotite.  The  groundmass  is  stained  a  yellowish-brown  in  many 
places. 

*  See  further  the  original  paper  of  vom  Rath.  Abhamllungen  ans  dem  Gc-bietn  tier  \atiir\vissenj-rhaftcii, 
M.-itlifiiiatili,  mill  Mriliciu  als  Gralulationssclirift  tier  uirilrrrhriiiisfhen  (icsi  llsc!i:ift  fur  Xatur-und  lleilkmitle 
zur  feier  des  fnn&igjahrigen  Jnliilaiims  tier  koiiijjlich  rheiuisclicu  Fricdrich-Wilhclms-Uiiiversitat.  Bouu. 
Ain  3  August,  1SG8,  pp.  135-1G1,  with  plate. 


96  PEEIDOTITE. 

The  enstatite,  pyroxene,  and  olivine  are  in  clear  grains  when  unstained,  and  are  much 
fissured  and  broken. 

Some  of  the  enstatite  shows  the  same  structure  as  the  chondri  of  other  meteorites 
except  that  it  wants  the  cementing  base.  That  is,  these  grains  are  formed  from  minute 
grains  arranged  in  rod-like  forms,  and  lying  side  by  side.  The  iron  and  pyrrhotite  is  in 
irregular  masses  and  granules.  Some  colorless  irregular  patches  were  observed,  giving 
a  pale  color  in  polarized  light  and  resembling  nephelite. 

Figure  1,  Plate  IV.,  shows  the  general  structure  of  the  groundmass,  with  its  inclusions 
of  iron,  pyrrhotite,  etc.,  and  its  ferruginous  staining.  This  groundmass  is  fine-granular, 
with  some  traces  of  chondritic  structura 

Mocs,  Transylvania. 

This  meteorite  has  been  described  by  Koch,  Tschermak,  and  Brezina,  and  the  follow- 
ing is  condensed  from  Tschermak's  description.  On  the  fresh  fracture  the  rock  appears 
as  a  gray  and  white,  rough,  friable  mass,  flecked  with  little  brown  and  yellow  spots,  and 
traversed  by  fine  black  veins.  The  grayish-white  groundmass  contains  small  spherules 
of  varying  size,  small  grains  of  iron  and  pyrrhotite,  and  occasionally  larger  grains  of  iron. 
Those  chondri  which  are  granular  and  vary  from  a  white  to  a  yellowish  color  are  com- 
posed of  olivine,  but  those  of  a  white  color  and  of  a  fine  rod-like  or  fibrous  texture  are 
composed  of  enstatite.  Under  the  microscope  the  stone  was  found  to  contain  olivine, 
enstatite,  diallage,  plagioclase,  iron,  pyrrhotite,  rarely  chromite,  and  a  black  undetermined 
mineral.  The  olivine  is  pale-yellowish  green,  and  contains  irregular  inclusions  of  a  fine 
black  dust,  angular  black  grains,  and  glass.  The  enstatit0  has  a  pale-greenish  color,  and 
contains  brownish,  rounded  glass  inclusions,  spherical  and  lens-shaped  vapor  cavities,  and 
small  black  spheres.  The  diallage  contains  inclusions  of  abundant  black  dust  and  grains, 
and  glass,  with  some  microlites.  Part  of  the  diallage  presents  the  characters  of  diopside. 
The  plagioclase  appears  in  colorless  rounded  grainsr  containing  many  irregular,  brownish, 
glass  inclusions.  In  polarized  light  many  of  the  feldspars  show  well-marked  character- 
istic twinning.  The  iron  is  in  small  spheres  in  the  groundmass  and  in  the  chondri,  as 
well  as  in  rounded  and  elongated  rough  grains,  sometimes  showing  a  cubic  cleavage. 
The  pyrrhotite  occurs  in  minute  grains.* 

Zsaddny,  Temesvar  Comitat,  Banat. 

Dr.  E.  Cohen  made  a  microscopic  study  of  the  Zsadiiny  meteorite  in  1878.  Macro- 
scopically,  the  following  constituents  were  observed:  — 

1.  A  fine-crystalline,  light-gray  groundmass,  in  which  appeared  scattered  grains  with 
a  conchoidal  fracture  and  a  vitreous  lustre.     These  were  mostly  water-clear  or  else  of 
a  pale  honey-yellow  color. 

2.  Grains  of  the  color  of  pyrrhotite,  and  grains  or  leaves  of  nickeliferous  iron. 

3.  Numerous  dark  gray  crystalline  spherules,  with  a  rough  surface,  and  a  faint 
resinous  lustre   on   the   surface  of   fracture.     On  the   polished   surface   they   show  an 
elliptical  form. 

In  the  thin  section  two  classes  of  these  spherules  were  seen.  One  is  composed  of 
small  columns  of  an  enstatite-like  mineral.  This  contains  a  few  small  pores,  and 

*  Koch,  Min.  Mitth.,  1883,  v.  234-244;  Sitz.  Wieii.  Akad.,  1882,  Ixxxv.  1,  pp.  116-132;  Tschermak, 
ibid.,  pp.  195-209  ;  Breziua,  ibid.,  pp.  335-343. 


THE   METEORIC   PERIDOTITES.  —  LHEKZOLITE.  97 

between  the  columns  a  cloudy  substance  was  observed.  Cohen  is  in  doubt  whether  this 
substance  is  an  alteration-product  or  has  intruded. 

The  second  i.s  formed  from  aggregations  of  round  or  angular  olivine  grains  and  a 
cloudy  substance.  The  oliviue  and  eustatite  also  occur  in  the  groundrnass.  The  enstatite 
incloses  some  opaque  grains  and  colorless  microlites.  The  olivine  contains  some  porea 
which  are  for  the  most  part  empty,  but  some  of  them  appear  to  hold  a  little  fluid. 

Cohen  thought  that  an  accessory  mineral  observed  was  hypersthene.  Pyrrhotite  and 
nickeliferous  iron  were  also  seen.  Between  all  these  constituents  lies  a  cloudy,  very 
rarely  feebly  transparent  substance  which  appears  to  be  identical  with  that  observed  in 

the  spherules. 

Cohen  seems  to  adopt  the  mechanical  theory  for  the  origin  of  chondritic  structure, 
but,  following  Giimbel,  holds  that  the  eccentric  radiated  structure  of  many  of  the 
spherules  is  owing  to  a  secondary  formation.* 

Cohen's  cloudy  substance  is  doubtless  the  gray,  fibrous,  base  and  semi-base  observed 
by  the  present  writer  in  other  meteorites  —  like  the  Iowa  one,  for  instance. 

Esthcrvillc,  Emmet  Co.,  Iowa. 

The  Estherville  meteorite  has  a  grayish  granular  groundrnass,  holding  irregular  grains 
of  olivine  and  diallage.  The  olivine  grains  are  of  various  sizes,  from  minute  ones  to 
those  two  inches  in  diameter.  Scattered  through  the  mass,  in  irregular  nodular  jagged 
forms,  occurs  the  iron.  Some  bluish-gray  fragments  were  seen  inclosed,  but  of  an 
unknown  nature,  although  they  may  be  olivine.  The  groundmass  is  identical  in  appear- 
niicu  with  that  of  the  finer-grained  peridotites,  and,  excepting  the  iron,  the  rock  is  strik- 
ingly similar  to  some  from  North  Carolina, 

Two  or  three  patches  composed  of  yellowish-green  olivine,  and  a  glassy  white  mineral 
were  seen.  The  latter  resembles  feldspar  or  quartz,  but  it  would  probably  not  be  found 
in  the  section,  or  by  chemical  analysis,  unless  especial  portions  were  taken  for  examina- 
tion. The  iron  shows  imperfect  dodecahedral  forms  with  striated  faces.  One  imperfect 
fm  in  resembled  a  cube  face  modified  by  two  pentagonal  dodecahedral  planes.  A  few  small 
black  grains  were  seen  resembling  picotite  or  chromite.  The  crust  in  some  places  shows 
that  it  was  derived  from  the  fused  oliviue;  hence  if  the  fusion  point  of  this  olivine  could 
be  ascertained,  it  would  give  the  minimum  temperature  of  the  surface  during  its  passage 
through  the  air.  The  specimen  above  described,  in  the  Harvard  College  Cabinet,  is  said 
to  weigh  twenty-eight  pounds,  and  it  affords,  on  account  of  the  large  extent  of  its  frac- 
t lived  surface,  a  good  opportunity  to  study  the  macroscopic  characters  of  this  peridotite. 
This  specimen,  in  some  places,  shows  the  remains  of  an  internal  cavernous  structure,  its 
cell-walls  being  lined  with  minute  crystals. 

Section :  a  grayish  groundmass,  holding  grains  of  enstatite,  olivine,  and  diallage,  with 
iron  and  pyrrhotite.  The  groundmass  is  composed  of  a  crystalline,  granular  aggregate  of 
tln'-e  minerals. 

The  olivine  is  in  clear,  rounded  grains,  of  irregular  outline.  Lying  in  the  olivine 
are  numerous  grains  and  irregular  masses  of  iron,  which  are  usually  confined  to  certain 
portions  of  the  mineral,  and  are  wanting  in  some  crystals.  Besides  the  larger,  easily 
recognizable,  irregular,  semi-sponge-like  masses  of  iron  surrounding,  projecting  into,  or 
included  in  the  olivine,  drop-like  forms  are  seen  extending  in  irregular  bines  from 

«  Vcrh.  Natur.  Med.  Verciu,  Heidelberg,  1878,  ii.  (2),  154-163. 

13 


98  PEEIDOTITE. 

points  on  the  larger  iron  masses  through  the  silicate.  These  globules  are  of  every  size, 
from  those  whose  metallic  lustre  and  character  can  be  readily  recognized  with  low 
powers  to  those  that  remain  a  fine  dust  when  magnified  one-thousand  times.  It  cannot 
be  said  that  the  finer  dust-like  portions,  resembling  the  globules  in  the  basaltic  base,  are 
the  same  as  the  larger  globules  of  iron ;  but  the  gradual  transition  in  size  between  the 
grains  of  different  sizes,  and,  with  the  increase  in  power,  the  increase  in  number  of 
globules  that  can  be  recognized  as  metallic  iron  leads  one  to  suspect  that  all  these  gran- 
ules, whatever  may  be  their  size,  are  of  the  same  origin  and  material — iron.  These  forms, 
in  the  minute  state,  are  similar  to  some  of  the  inclusions  in  the  olivine  of  the  Cumber- 
land pallasite,  but  in  the  latter  case  the  iron,  if  occurring,  would  be  oxidized.  Some  of 
the  olivine  grams  show  a  fine  cleavage  adjacent  to  the  cross  fissures. 

The  enstatite  is  in  irregular  and  oval  masses,  with  a  perfect  longitudinal  cleavage  and 
a  cross  fracture.  The  extinction  takes  place  in  polarized  light  parallel  to  the  cleavage. 
The  enstatite  contains  inclusions  of  olivine  and  of  iron,  the  same  as  previously  described 
in  the  olivine. 

The  diallage  has  an  irregular  longitudinal  cleavage,  its  forms  being  the  same  as  those 
of  the  enstatite.  The  cleavage  lines  of  the  diallage  are  either  cut  by  irregular  cross- 
fractures,  or  connect  by  oblique  fissures,  so  as  to  give  an  irregular  network  over  the  face, 
rendering  it  more  obscure  and  cloudy.  The  extinction  is  oblique  to  the  principal 
cleavage  planes.  It  contains  the  same  inclusions  as  the  enstatite.  While  the  olivine, 
enstatite,  and  diallage  are  all  clear,  transparent,  and  colorless  in  the  thin  section,  yet 
their  cleavage  characters  are  so  distinct  that  in  general  they  can  readily  be  distinguished 
from  one  another  without  the  use  of  polarized  light. 

The  iron  and  pyrrhotite  are  in  detached  granules,  droplets,  irregular  jagged  masses, 
and  in  imperfect  sponge-like  forms.  In  some  cases  they  form  an  irregular  net-work  in 
the  groundmass,  and  in  an  imperfect  ring  surround  the  larger  grains  of  olivine,  enstatite, 
and  diallage.  The  material  for  the  above  described  sections  was  purchased  from  W.  J. 
Knowlton  of  Boston. 

Figure  5,  Plate  III.,  represents  a  central  crystal  of  diallage  with  the  surrounding 
groundmass  of  oliviue,  enstatite,  diallage,  iron,  pyrrhotite,  and  the  ferruginous  staining. 

Figure  6,  Plate  III.,  shows  the  semi-sponge-like  mass  of  iron  and  pyrrhotite  with 
their  inclosed  silicates,  forming  a  groundmass  holding  two  porphyritic  crystals  of  dial- 
lage and  enstatite,  showing  their  characteristic  cleavages  and  inclusions,  although  the 
latter  are  imperfectly  represented. 

Attention  was  originally  called  to  this  very  interesting  meteorite  by  Prof.  S.  F.  Peck- 
ham,  who  stated  that  a  preliminary  examination  showed  that  the  metallic  portion  was 
an  alloy  of  iron,  nickel,  and  tin.  "  Full  half  the  mass  consists  of  stony  matter  which 
appears  in  dark-green  crystalline  masses  embedded  in  a  light-gray  matrix.  .  .  .  Some 
of  the  crystalline  masses  are  two  inches  in  thickness,  and  exhibit  distinct  monoclinic 
cleavage.  Under  the  microscope,  in  thin  sections,  olivine,  and  a  triclinic  feldspar  appear 
to  be  imbedded  in  a  matrix  of  pyroxene.  ...  A  small  piece  of  the  metal  polished 
and  etched  exhibited  the  Widmanstattian  figures  very  finely."*  Prof.  C.  U.  Shepard,  in 
the  same  volume  (pp.  186-188),  gives  a  further  description  of  this  meteorite.  He  writes: 
"  It  is  marked  by  the  unusual  prevalence  of  chrysolite  and  meteoric  iron,  the  former 
probably  constituting  two-thirds  its  bulk ;  also  by  the  size  and  distinctness  of  the 
chrysolitic  individuals,  together  with  their  pretty  uniform,  yellowish-gray  or  greenish- 

*  Am.  Jour.  Sci.,  1879  (3),  xviii.  77,  78. 


THE   METEORIC   PERIDOTITES.  —  LHERZOLITE.  99 

Mack  color;  and  by  the  ramose  or  branching  structure  of  the  meteoric  iron.  Nearly 
line-half  of  the  chrysolite,  however,  is  more  massive,  approaching  tine-granular,  or  com- 
pact. Yet  in  this  ciuiditiou  it  is  still  highly  crystalline,  and  difficultly  frangible.  This 
portion  is  of  an  ash-gray,  flecked  with  specks  of  a  dull  greenish-yellow  color.  The 
lustre  is  feebly  shining.  .  .  .  Especially  is  it  observable  that  the  stony  portions  nowhere 
present  traces  of  the  oolitic,  or  semi-porphyritic  structure,  so  common  in  meteoric 
stones.  .  .  . 

"  The  meteoric  iron,  besides  being  in  ramose  branches,  is  also  in  enveloping  coatings 
around  the  chrysolite,  somewhat  as  in  the  Pallas  and  Atacama  irons.  .  .  .  The 
presence  of  schreibersite  in  the  metal  is  apparent  to  the  naked  eye."  The  minerals  that 
Shepard  supposed  that  he  found  were  chrysolite,  schreibersite,  chromite,  troilite,  a  "  felds- 
pathic  mineral,  presumably  anorthite,"  and  an  "  opal-like  mineral  of  a  yellowish-brown 
color,  which  I  take  to  be  chassignite." 

Later,  J.  Lawrence  Smith  made  a  further  examination  of  the  Estherville  meteorite.* 
He  found  olivine,  bronzite,  nickeliferous  iron,  troilite,  chromite,  and  an  opalescent  silicate. 
The  last  has  a  light,  greenish-yellow  color,  and  cleaves  readily.  It  was  regarded  as 
formed  from  one  atom  of  bronzite  plus  one  atom  of  olivine.  Smith  further  says :  "  I 
examined  carefully  for  feldspar  and  schreibersite,  but  the  absence  of  both  limp,  and  alu- 
mina (except  as  a  trace)  clearly  proved  the  absence  of  anorthite ;  and  the  small  particles 
of  the  mineral  that  might  have  been  taken  for  schreibersite,  were  found  on  examination 
in  all  instances  to  be  troilite." 

Dr.  Smith's  chemical  analysis  was  made  in  such  a  manner  that  it  is  impossible  from 
it  to  draw  any  conclusions  as  to  the  relative  proportion  of  the  elements  in  the  mass  as 
a  whole. 

Later,!  Smith  named  the  " opalescent  silicate"  pcckhamitc,  and  thought  from  his 
farther  analyses  that  it  was  probably  composed  of  two  atoms  of  bronzite  to  one  of  oli- 
vine 

In  1882  Dr:  Stanislas  Meunier  described  the  microscopic  characters  of  the  Estherville 
peridotite,  which  he  referred  to  the  logronite  type  of  meteorites  —  one  of  the  43  types 
proposed  by  him  in  1870.  \  He  found  the  following  minerals :  olivine,  bronzite,  peck- 
hamite  ?  pyrrohotite,  schreibersite,  magnetite,  and  nickeliferous  iron. 

The  olivine  is  in  very  large  crystalline  fragments,  yielding  in  polarized  light  a  most 
brilliant  colored  mosaic.  In  common  light  they  are  colorless,  often  cleaved  and  filled 
with  crystalline  inclusions.  Liquid  bubbles  in  spheroidal  cavities,  remarkable  for  their 
large  size,  were  seen.  In  converging  light  the  crystals  show  two  systems  of  brilliant 
riiii^,  whose  axes  show  strong  dispersion. 

The  bronzite  is  in  poorly  formed  crystals,  clearly  dichroic,  and  showing  a  well-marked 
parallel  rectilinear  cleavage. 

The  pcckhamite  is  in  large,  feebly  colored  crystals,  composed  of  alternations  of  laminae, 
inversely  affecting  polarized  light.  The  action  of  acids  upon  them  causes  one  to  regard 
this  mineral  as  composed  of  extremely  thin  interlaminated  layers  of  bronzite  and  olivine. 

The  magnetite  is  in  perfect  octahedrons. 

jr.  Meunier  concludes  as  follows:  "  In  presence  of  these  different  characters  of  com- 
position and  structure,  it  is  seen  that  the  identity  is  complete  with  the  logronite  already 

»  Am.  Jour.  Sci.,  1S80  (3),  xix.  459-403,  495,  490. 

t  Am.  Jonr.  Sci.,  1880  (3),  xx.  136,  137. 

t  Cosmos,  1870  (3),  vi.  70-73,  95-98,  152-155,  186-188,  210-215. 


100  PERIDOTITE. 

described.  We  must  believe  with  respect  to  the  Estherville  form,  that  the  primitive 
mass  in  the  condition  of  debris,  in  part  stony,  in  part  metallic,  accumulated  in  some 
crevice,  has  been  subjected  to  metalliferous  emanations,  of  which  the  product,  under  the 
form  of  a  fine  network,  has  soldered  together  the  components  previously  disconnected. 
The  spaces  —  so  remarkable  —  existing  sometimes  between  the  modules  of  iron  and  their 
rocky  matrix,  are  artificially  reproduced  in  the  process  of  metallic  cementation  of  the 
dust  of  peridot,  by  a  method  which  I  have  already  described."  * 

The  present  writer  finds  himself  obliged  to  dissent  from  M.  Meunier's  views  regarding 
the  origin  of  this  meteorite,  for  the  following  reasons :  He  (the  writer)  can  nowhere 
in  the  sections  find  any  evidence  that  its  materials  ever  held  any  different  relation  than 
the  present,  and  no  sign  of  a  former  fragmental  state  is  observable  to  him ;  but  he  does 
see  evidence  that  is  convincing  to  him  that  the  entire  mass  has  been  formed  by  cotem- 
poraneous  crystallization,  i.  e.,  it  has  the  same  structure  that  a  terrestrial  lava  of  the 
same  composition,  cooling  under  conditions  that  would  allow  the  entire  mass  to  crystal- 
lize, would  have.  The  inclusion  of  the  iron  in  the  silicates,  indicating  their  later  solidifi- 
cation, would  show  that  the  iron  was  not  a  posterior  emanation.  Such  a  formation  as 
M.  Meunier  supposes  could  not  take  place  without  leaving  a  record  behind  of  its  action. 

It  has  been  hoped  that  a  complete  microscopic  description  would  have  been  pub- 
lished by  Professor  C.  W.  Hall,  of  the  University  of  Minnesota  (see  Professor  Peckham's 
paper  before  referred  to,  page  98) ;  but  thus  far  he  has  been  unable  to  get  time  for  the 
work.  Professor  Hall  has  very  kindly  sent  me  some  of  his  sections  for  examination, 
and  the  additional  information  obtained  from  them  is  given  below. 

The  sections  sent  by  Professor  Hall  are,  in  their  general  and  mineralogical  char- 
acters, so  unlike  those  already  described,  that  were  it  not  for  the  source  from  which 
they  were  obtained,  it  would  be  very  difficult  to  believe  that  they  came  from  the  same 
meteorite. 

They  have  a  confused  light-greenish-yellow  groundmass,  holding  irregular  masses  of 
olivine,  enstatite,  and  feldspar.  The  groundmass  appears  to  be  composed  of  olivine, 
enstatite,  feldspar,  pyrrhotite,  and  magnetite.  But  little  native  iron  is  to  be  found  in  the 
sections.  The  groundmass  is  stained  a  ferruginous  yellow  in  many  places,  and  the  com- 
mencement of  a  serpentinous  alteration  was  seen  in  some  of  the  olivines. 

The  feldspar  is  in  irregular  glassy  masses,  and  in  imperfect  crystals,  showing  stria- 
tion  and  extinction  oblique  to  the  nicol  diagonal.  They  contain  inclusions  apparently  of 
olivine,  enstatite,  magnetite,  bubble-bearing  glass  cavities,  etc. 

The  olivine  and  enstatite  contain  also  glass  inclusions,  magnetite,  etc.  The  enstatite 
in  some  places  is  diehroic  along  its  cleavage  planes,  owing  to  its  slight  greenish  altera- 
tion. 

These  sections,  having  been  prepared  by  a  student,  are  of  such  thickness,  and  ground 
with  so  uneven  a  surface,  that  the  study  of  them  is  very  difficult.  A  few  grains  resem- 
ble quartz,  but  they  are  probably  unstriated  glassy  feldspars.  My  thanks  are  due  Pro- 
fessor Hall,  and  I  regret  that  I  cannot  profit  more  by  his  kindness.  These  sections  are 
so  much  unlike  those  previously  described,  that  I  trust  he  will  have  further  and  thinner 
sections  made,  and  publish  a  complete  description  of  them  himself,  t 

From  the  various  descriptions  given  it  is  to  be  concluded  that  the  Estherville  perido- 
tite  varies  considerably  in  its  mass,  in  different  portions  —  from  those  parts  entirely  iron, 

*  Comptes  Rendus,  1882,  xciv.  1659-1661. 

f  It  is  probable  from  their  alteration  that  the  material  from  which  these  sections  were  made  had  beeu 
exposed  to  atmospheric  agencies  for  some  time. 


THE   METEORIC   PERIDOTITES.  —  BUCHNERITE.  101 

those  of  a  sponge-like  iron  mass  holding  silicates,  those  of  but  little  iron  with  the  sili- 
cates, and  those  that  are  pure  or  nearly  pure  silicates.  If  detached  portions  should  be 
taken  and  analyzed  chemically  and  microscopically,  it  could  be  claimed  that  this  meteorite 
is  a  siderolite  —  a  pallasite  —  a  peridotite,  and  all  be  equally  correct  so  far  as  the  portion 
examined  would  show;  but  studying  this  meteorite  as  a  whole,  its  proper  place  both 
chemically  and  microscopically  appears  to  be  with  the  peridotites.  The  variations  in  the 
descriptions  given  by  the  different  observers  who  have  examined  this  meteorite,  are 
doubtless  owing,  in  many  cases,  to  the  actual  variation  in  the  rock  itself.  It  offers  a 
striking  illustration  of  the  need  of  some  more  general  method  than  a  purely  mineralogi- 
cal  one  in  naming  rocks. 

Since  the  preceding  was  written,  specimens  of  this  meteorite,  containing  peckhamite, 
have  been  received  from  Professor  Peckham.  The  sections  present  for  the  mass  of  the 
meteorite  the  same  composition  and  structure  as  those  obtained  from  Professor  Hall. 
The  peckhamite  presents  the  optical  characters  and  cleavage  of  enstatite,  but  is  filled 
entirely  full  of  vapor  cavities,  iron,  glass,  brown  grains,  etc.  To  these  inclusions  is  appar- 
ently owing  the  coloid  appearance  of  peckhamite, and  the  variation  in  its  analysis;  while 
Meunier  probably  mistook  plagioclase  for  this  mineral 


VARIETY.  —  Buchnerite. 

Ticschitz,  Moravia. 

A  microscopic  study  of  the  Tieschitz  meteorite  has  been  made  by  A.  Makowsky  and 
G.  Tschermak.  The  color  of  the  meteorite  on  its  inner  surface  is  ash-gray,  and  it  has 
a  chondritic  structure.  It  shows  many  minute  deep-gray,  or  dark-colored  globules  and 
splinters,  and  occasionally  larger  spherules  of  the  same  color  ;  also,  little  white  globules 
and  fragments,  which  are  subordinate  in  amount  to  the  former.  Lying  between  them 
were  seen  an  ash-gray  earthy  groundmass,  and  a  very  few  yellowish  particles  showing 
metallic  lustre.  Certain  characters  of  some  of  these  spherules  had  never  been  described 
previously  in  any  other  meteorite.  Some  show  a  concave  impression  upon  them,  indi- 
cating plasticity  during  their  formation.  Some  of  these  latter  spherules  also  show  out- 
side of  these  concavities  an  excrescence  having  a  round  or  pointed  termination.  These 
characters  not  harmonizing  well  with  Tschermak's  friction  theory  of  the  formation  of 
the  globules,  which  will  be  later  given  in  this  work,  (pp.  109,  110),  he  adopted  a  new 
theory,  that  while  these  grains  are  the  result  of  volcanic  eruption  and  explosion,  their 
form  could  be  derived  from  their  plastic  condition,  instead  of  from  the  friction  of  solid 
particles  as  he  had  held  before. 

The  general  characters  of  the  meteorite  were  much  the  same  as  those  of  the  preced- 
ing. Olivine,  bronzite,  enstatite,  augite,  pyrrhotite,  and  nickeliferous  iron  were  the  min- 
eral constituents  observed. 

The  olivine  was  found  in  the  groundmass,  and  in  some  of  the  spherules.  Inclusions 
of  black  angular  grams,  and  of  brownish  glass  with  fixed  bubbles,  were  seen. 

The  bronzite  is  principally  in  stalk-like  and  fibrous  forms.  It  contains  also  inclus- 
ions of  brown  glass,  with  immovable  bubbles. 

The  enstatite  has  about  the  same  form  as  the  bronzite,  contains  the  same  inclusions, 
and  is  white  or  of  a  pale  color.  It  occurs  in  chondri  and  fragments.  Augite  was  found 
in  small  amounts  in  globules,  having  the  same  inclusions  as  the  olivines. 


102  PE1UDOTITE. 

The  pyrrhotite  occurred  in  small  grains,  not  only  in  inclusions  in  the  globules  and 
fragments,  but  also  in  the  groundmass. 

The  iron  is  mostly  in  irregular  pronged  particles  in  the  groundmass.  * 

Hungen,  German//. 

The  Hungen  meteorite  has  been  described  both  by  Buchner  and  Tschermak.  Tscher- 
mak  stated  that  the  section  showed  quite  large  particles  of  iron,  a  few  small  grains  of 
magnetite,  with  fragments  of  minerals  and  spherules  in  the  groundmass4.  Some  small 
untransparent  grains  without  metallic  lustre  were  thought  to  be  chromite  or  picotite. 

The  other  minerals  were  olivine  and  bronzite,  besides  brown  angular  grains  that 
were  supposed  to  be  augite.  This,  like  nearly  all  the  meteoric  peridotites,  is  ehondritic. 
Needles  and  grains  of  a  water-clear  mineral,  and  fine  grains  of  chromite  were  seen  in 
the  olivine.  The  enstatite  contained  brown  needles  and  grains,  as  well  as  the  chromic 
iron  dust.f 

Grosnaja,  Caucasus. 

The  color  of  the  interior  of  the  Grosnaja  meteorite,  according  to  Tschermak,  is  a 
blackish-gray,  sprinkled  with  clear  to  whitish-colored  points.  In  the  section  the 
groundmass  is  black  and  opaque,  while  many  of  the  inclusions  were  either  opaque  or 
transparent  only  in  spots.  Other  inclusions  were  transparent,  and  showed  mostly  a 
spheroidal  structure,  although  a  few  pieces  were  angular. 

Tschermak  distinguished  five  different  minerals :  a  clear-green  olivine,  bronzite, 
augite,  pyrrhotite,  and  a  carbonaceous  mineral.  Iron  in  very  small  amounts  was  also 
found. 

This  meteorite  showed  chondritic  structure,  as  seems  to  be  usual  with  the  olivine- 
enstatite  ones.J 

Alfianello,  Brescia,  Italy. 

This  meteorite  has  been  microscopically  studied  by  Baron  von  Foullon.  It  has  a 
chondritic  structure  and  is  composed  of  nickeliferous  iron,  olivine,  bronzite,  an  augitic 
mineral,  pyrrhotite,  and  maskelynite.  The  fresh  fracture  shows  a  pale-grayish  white 
finely  crystalline  surface  sprinkled  with  pyrrhotite.  The  olivine  is  of  a  light  color  and 
generally  in  grains.  The  bronzite  is  somewhat  of  a  light-yellowish  to  brownish-yellow 
color,  and  shows  cleavage  lines.  The  maskelynite  was  found  as  an  intergrowth  with  the 
bronzite,  occurring  as  a  colorless,  water-clear  substance. 

The  chondri  are  irregular  and  show  about  the  usual  structural  varieties.  § 

*  Denks.  Wien.  Akad.,  1879,  xxxix.  (2),  187-202,  5  plates  ;   Sitz.  "Wien.  Akad.,  1878,  Ixxviii.  (1), 
440-443,  580-582  ;  Verb.  Nat,  Verein,  Briiun,  1879,  xviii.  40,  41. 
f  Mill.  Mittli.,  1877,  pp.  313-310. 
%  Min.  Mitth.,  1878  (2),  i.  153-164. 
§  Sitz.  Wien.  Akad.,  1883,  Ixxxviii.  (1),  433-143. 


THE  METEORIC   PERIDOTITES.  103 


MISCELLANEOUS. 

Bavarian  Meteorites. 

In  1878  Prof.  C.  W.  Giimbel  gave  an  account  of  his  microscopic  examination  of  five 
meteorites  that  had  fallen  in  liavaria  at  different  dates  during  the  18th  and  19th 
centuries.  Four  of  these  are  described  below,  and  one  later  under  The  Basalts. 

1.    The  MaucrkirscJicn  Meteorite. 

This  rock  is  of  a  light-gray  color,  with  black  spots  of  metallic  iron,  which  in  places 
show  oxidation.  It  has  a  very  fine-grained  groundmass,  which  incloses  blackish  and 
yellowish  grains.  The  stone  shows  the  chondritic  structure,  and  has  the  usual  charac- 
ters. The  groundmass  contains  fragments  and  grains  of  the  various  minerals. 

Giimbel  holds  that  this  meteorite  contains  olivine,  a  feldspathic  and  an  augitic 
mineral,  pyrrhotite,  chromite,  and  iron. 

2.    The  Eiclistadt  Meteorite. 

This  rock  also  belongs  to  the  chondritic  meteorites,  and  was  thought  by  Giimbel  to 
contain  an  augitic  and  two  feldspathic  minerals,  as  well  as  olivine,  iron,  pyrrhotite,  and 
chromite. 

3.  TJie  Schoncnberg  Meteorite. 

This,  like  the  preceding,  belongs  to  the  chondritic  type,  and  was  thought  by  Gtimbel 
to  contain  the  following  minerals:  olivine,  iron,  pyrrhotite,  chromite,  schreibersite,  a 
feldspathic,  a  scapolitic,  and  an  augitic  mineral 

4.  The  Krdhenbcrg  Meteorite. 

According  to  Giimbel  this  chondritic  rock  contained  olivine,  pyrrhotite,  iron,  chromite, 
an  augitic  mineral  (bronzite  ?)  and  a  feldspathic  mineral  (Labrador  ?).* 

It  is  not  probable  that  the  meteorites  above  described  by  Giimbel  in  reality  differ 
much  in  mineralogical  characters  from  the  common  forms,  the  determinations  being  here 
thought  to  be  imperfect.  It  is  therefore  to  be  hoped  that  in  the  light  of  the  advances 
made  in  the  knowledge  of  the  microscopic  characters  of  minerals,  a  reexamination  will 
be  made  to  these  meteorites. 

Charlottdown,  Cabarras  Co.,  North  Carolina. 

This  stone  is  described  as  having,  on  the  fresh  fracture,  a  dark,  bluish-gray  ground- 
inns*,  holding  porphyritically  inclosed  crystals  and  grains  of  a  grayish-white  mineral, 
with  a  tin^'c  of  lavender-bluet 

The  specimen  in  the  Harvard  College  Cabinet  shows  the  usual  chondritic  structure, 
and  contains  considerable  iron.  The  grayish-white  minerals,  with  a  tinge  of  lavender- 
blue,  are  the  chondri,  which  are  well  marked  in  this  meteorite.  It  possesses  a  striking 

*  Sitz.  Miinchcn  Akail.,  1S78,  viii.  lt-72. 

f  C.  U.  Shcpard,  Proc.  Am.  Assoc.  Adv.  Sci.,  1850,  iii.  149-152. 


104  PERIDOTITK 

similarity  to  the  Iowa  Co.  meteorite,  although  the  chondri  are  somewhat  smaller. 
Judging  from  the  general  characters  of  the  Cabarras  meteorite,  it  is  probable  that 
Shepard's  analysis  is  incorrect,  and  it  is  hoped  a  new  one  will  be  made. 

Other  specimens  of  meteoric  peridotites  in  the  Harvard  College  Mineral 
Cabinet,  macroscopically  examined  by  the  writer,  are :  — 

Mezo-Madaras,  Transylvania. 

This  shows  a  somewhat  coarse  chondritic  structure,  and  contains  grains  of  iron  and 
pyrrhotite. 

Alessandria,  Piedmont. 

This  has  a  grayish  groundmass  showing  an  imperfect  chondritic  structure,  and  con- 
tains considerable  iron  in  grains  and  in  films  running  through  it. 

Rcnazzo,  Ferrara,  Italy. 

This  has  a  dark  surface  or  groundmass,  holding  grayish-white  rounded  grains  or 
chondri.  Since  this  specimen  shows  no  fresh  fracture,  but  little  can  be  said  about  its 
characters.  It  resembles  closely,  in  external  appearance,  some  of  the  Cordilleran 
andesites,  possessing  a  dark,  glassy  groundmass  holding  rounded,  glassy  feldspars. 

This  meteorite  has  been  described  before  as  similar  to  an  obsidian-porphyry  and 
possessing  a  compact,  black,  enamel-like  groundmass,  holding  numerous  light-gray 
spherules.* 

This  meteorite  ought  to  be  studied  microscopically,  for  it  promises  to  be  one  of  the 
most  interesting  specimens  examined  by  that  method,  and  will  probably  throw  much 
light  upon  the  origin  of  meteorites,  especially  if  it  should  prove  to  be.  as  it  appears,  less 
devitrified  than  other  meteorites  microscopically  examined. 

Hartford,  Linn  Co.,  Iowa. 

This  has  a  light-gray  granular  groundmass  showing  chondritic  structure,  and  is 
sprinkled  with  metallic  particles. 

Ausson,  Haute  Garonne,  France. 

The  specimen  shows  a  gray  groundmass,  and  possesses  a  well-marked  chondritic 
structure. 

Nanjemoy,  Maryland. 
This  is  the  same  as  the  Ausson  rock,  except  that  its  structure  is  of  a  finer  character. 

Drake  CrecJc,  Simmer  Co.,  Tennessee. 

This  has  a  light-gray,  fine-granular  groundmass,  sprinkled  with  iron  in  various  forms. 
This  stone  closely  resembles  that  from  Hartford,  Linn  Co.,  Iowa. 

*  Buclmer,  Meteoriten  in  Sammlungen,  1863,  pp.  46,  47. 


THE   METEORIC    PERIDOTITES.  — TUFA.  105 

L'Aiglc,  Onie,  France. 

This  possesses  a  gray  groundmass,  holding  chondrL  One  of  the  chondri  shows  a 
concave  depression,  the  same  as  those  described  by  Tschermak  as  occurring  in  the 
Tieschitz  meteorite.  (See  ante,  page  101.) 

Weston,  Connecticut. 

This  shows  the  same  gray  groundmass  as  the  preceding,  and  an  excellently  developed 
chondritic  structure. 

Chateau  Itcnard,  France. 

This  has  a  light-gray  groundmass,  sprinkled  with  metallic  points. 

Hcsslc,  Sweden. 
This  has  a  grayish  chondritic  groundmass. 

Nobleboro\  Maine. 

This  specimen  is  apparently  fragmental  in  character,  and  closely  resembles  a  trachytic 
or  rliyolitic  ash.  The  specific  gravity,  according  to  Webster,  is  2.08,  but,  according  to 
I!  iimler,  3.092.  It  is  probable  that  Webster's  chemical  analysis  is  not  correct,  the  speci- 
men, if  authentic,  not  bearing  out  any  such  analysis  as  that  published  by  him.* 

This  meteorite  ought  to  be  reexamined  chemically,  and  studied  microscopically. 

VARIETY.  —  Tufa. 

Orvinio,  Haltj. 

The  structure  of  the  Orvinio  meteorite  is  described  by  Tschermak  as  uncommon  and 
remarkable.  The  rock  is  composed  of  clear-colored  fragments,  surrounded  by  a  compact, 
dark,  cementing  mass. 

The  fragments  are  yellowish-gray,  and  contain  spherules  and  particles  of  iron  and 
pyrrhotite.  The  cementing  material  is  blackish,  compact,  and  splintry,  holding  nearly 
uniformly -distributed  particles;  and  near  its  contact  with  the  fragments  shows  an 
evident  fluidal  structure.  This  makes  it  in  the  highest  degree  probable  that  the  cement- 
ing material  was  once  in  a  plastic  condition  and  in  motion.  The  fragments  are  darker, 
harder,  and  more  brittle  at  the  junction  with  the  inclosing  mass  than  they  are  in  the 
middle.  From  this  it  would  seem  that  the  matrix  had  been  at  a  very  high  temperature 
when  plastic. 

The  fragments  and  matrix  both  have  almost  the  same  composition,  density,  and 
mineral  characters. 

This  meteorite  resembles  a  volcanic  rock  in  which  a  fine  matrix  holds  fragments  of 
rock  of  the  same  character.  The  structure  is  the  same  as  it  is  when  a  younger  compact 
lava  breaks  through  an  older  and  more  crystalline  one. 

The  fragments  have  the  usual  chondritic  structure.  They  contain,  besides  iron  and 
pyrrhotite,  oliviue,  bronzite  (enstatite),  and  possibly  some  feldspar.  For  the  further 

«  Bost.  Jour.  Phil.,  1824,  i.  3SG-389;  Buchner,  Mcteoriteu  in  Saminlungeu,  1863,  p.  46. 

14 


10G  THE  METEOEITES.— THEIE   ORIGIN   AND   CHARACTER. 

description  and  figures  the  reader  is  referred  to  the  original  paper.  *  If  Tscherrnak  is 
correct  this  meteorite  must  have  come  from  a  body  either  partly  solid  and  partly  liquid, 
or  one  in  which  cooler  fragments  fell  into  the  liquid  mass. 

Chantonnay,  Vendee,  France. 

This  is  described  by  Tschermak  as  composed  of  olivine,  bronzite,  a  finely-fibrous 
translucent  mineral,  nickeliferous  iron,  and  pyrrhotite.  Its  structure  is  similar  to  the 
Orvinio  meteorite ;  that  is,  is  composed  of  chondritic  fragments  cemented  together  by  a 
black,  glassy  and  semi-glassy  material,  f 


SECTION'  III.  —  The  Meteorites.  —  Their  Origin  and  Character. 

IT  is  thought  most  convenient  to  ente'r  upon  these  questions  here  in  con- 
nection with  the  Largest  class  of  authenticated  meteorites.  And  in  doing 
this  the  views  of  those  persons  who  have  studied  them  microscopically  will 
be  especially  referred  to. 

Professor  N.  S.  Maskelyne  taught,  in  1863,  regarding  the  chondritic  meteo- 
rites :  — 

"  that  there  have  been  stages  in  the  progress  of  the  slag-like  mass  from  the  first  origin  of 
the  spherule  —  in  perhaps  a  seething  lake  of  mixed  and  molten  metals  on  which  a  rare 
oxygenous  atmosphere  was  acting  and  fermenting  out  as  it  were  the  more  oxidizable  ele- 
ments —  to  the  final  state  of  compact  continuity  in  which  the  spherules  are  found  agglu- 
tinated toether  or  imbedded  in  a  mama  of  mineral."  \ 


The  previous  year  he  had  said  :  — 

"  The  spherules  which  characterize  this  structure  are  often  composed  of  a  single  crys- 
talline and  homogeneous  mineral,  with  a  radiating  structure  ;  often  they  are  breccias 
made  up  of  several  crystals  of  the  same  or  of  different  minerals  united  by  a  granular 
network  of  mineral.  These  spherules  are  often  surrounded  by  a  shell  of  meteoric  pyrites 
or  iron,  and  are  set  in  a  mixed  mass,  often  highly  porphyritic,  composed  of  similar  ingre- 
dients with  the  spherules.  The  solidification  of  this  ground-mass  marks,  probably,  a 
second  stage  in  the  history,  the  former  indicating  the  very  gradual  separation  by  cooling 
of  some  of  the  ingredients  of  the  aerolite,  and  the  latter  the  result  of  the  further  gradual 
cooling  of  the  residuary  mass.  There  is  no  glass  or  uncrystallized  matter  apparent  in 
any  aerolite  yet  examined."  § 

Professor  Maskelyne's  views  were  set  forth  again  in  1875,  but  with  great 
caution  and  indefmiteness.  The  following  extract  gives  the  chief  additional 
point  bearing  on  the  chondritic  structure  :  — 

"  We  may,  perhaps,  go  so  far  as  to  suppose  that  if  groups  of  the  individual  particular 
units  of  a  meteor  cloud  once  should  approach  each  other  to  a  distance  small  enough  to 

*  Sitz.  Wien.  Akad.,  1874,  Ixx.  (1),  459-465.  f  Site.  Wien.  Akad.,  1874,  Ixx.  (1),  465-472. 

{  Phil.  Mag.,  1863  (4),  xxv.  440.  §  Proc.  Brit.  Assoc.,  1S62,  xxxii.  (scot.)  188-191. 


SOllBY'S   VIEWS.  107 

<_;ive  tlu-ir  mutual  gravitation  a  sensible  influence,  they  might  gradually  collect  into 
masses,  and  acquire  a  cohesion  more  or  less  compact  according  to  the  conditions  imposed 
on  such  masses  during  their  subsequent  history.  .  .  .  We  may,  indeed,  assert  that  the 
meteorites  we  know  have,  probably  all  of  them,  been  originally  formed  under  conditions 
from  which  the  presence  of  water,  or  of  free  oxygen,  to  the  amount  requisite  to  oxidize 
entirely  the  elements  present  were  excluded ;  for  this  is  proved  by  the  nature  of  the 
minerals  constituting  the  meteorites,  and  by  the  way  hi  which  the  metallic  iron  is  dis- 
tributed through  them.  " 

In  1864,  Mr.  H.  C.  Sorby  announced  the  presence  of  gl<oss  and  gas  cav- 
ities in  the  olivine  of  meteorites.  He  stated  that 

"  the.  vitreous  substance  found  in  the  cavities  is  also  met  with  outside  and  amongst  the 
crystals,  in  such  a  manner  as  to  show  that  it  "is  the  uncrystalline  residue  of  the  material 
in  \\hieh  they  were  formed.  ...  It  is  of  a  claret  or  brownish  color,  and  possesses  the 
characteristic  structure  and  optical  properties  of  artificial  glasses." 

Of  the  chondritic  structure  Mr.  Sorby  says,  it  appears  that 

"  after  the  material  of  the  meteorites  was  melted,  a  considerable  portion  was  broken  up 
into  small  fragments,  subsequently  collected  together,  and  more  or  less  consolidated  by 
mechanical  and  chemical  actions.  .  .  .  Apparently  this  breaking  up  occurred  in  some 
cases  when  the  melted  matter  had  become  crystalline,  but  in  others  the  forms  of  the 
j >;n tides  lead  me  to  conclude  that  it  was  broken  up  into  detached  globules  whilst  still 
melted."  f 

The  same  year  Mr.  Sorby  remarked  that  the  earliest  condition  of  meteo- 
rites was  that  of  igneous  fusion,  but  he  thought  that  the  Pallas  iron  afforded 

"physical  evidence  of  having  been  formed  where  the  force  of  gravitation  was  much 
smaller  than  on.  our  globe,  either  near  the  surface  of  a  very  small  planetary  body,  or 
towards  the  centre  of  a  larger,  which  has  since  been  broken  into  fragments."  f 

In  1865,  Mr.  Sorby  developed  his  views  still  further,  stating :  — 

"  The  character  of  the  constituent  particles  of  meteorites  and  their  general  microscopi- 
cal structure  differ  so  much  from  what  is  seen  in  terrestrial  volcanic  rocks,  that  it 
appears  to  me  extremely  improbable  that  they  were  ever  portions  of  the  moon,  or  of  a 
planet,  which  differed  from  a  large  meteorite  in  having  been  the  seat  of  a  more  or  less 
modified  volcanic  action.  A  most  careful  study  of  their  microscopical  structure  leads  me 
to  conclude  that  their  constituents  were  originally  at  such  a  high  temperature  that  they 
were  in  a  state  of  vapour,  like  that  in  which  many  now  occur  in  the  atmosphere  of  the 
sun.  .  .  .  On  cooling,  this  vapour  condensed  into  a  sort  of  cometary  cloud,  formed  of  small 
crystals  and  minute  drops  of  melted  stony  matter,  which  afterwards  became  more  or  less 
dcvitritied  and  crystalline.  This  cloud  was  in  a  state  of  great  commotion,  and  the  parti- 
cles moving  with  great  velocity  were  often  broken  by  collision.  After  collecting  together 
to  form  larger  masses,  heat,  generated  by  mutual  impact,  or  that  existing  in  other  parts 

*  Nature,  1S7.J,  xii.  485-437,  504-507,  520-523. 

f  Pn>c.  liny,  s*.,  18G3-64,  xiii.  333,  334;  Phil.  Mag.,  1804  (4),xxviii.  157-159;  Report  Brit.  Assoc., 
1865,  xxxv.  13"9,  140. 

J  (imi.  MM-.,  1864  (1),  i.  240,  241 ;  Report  Brit.  Assoc.,  18C4,  xxxiv.  (sect.)  70. 


108  THE  METEORITES.  —  THEIR   ORIGIN   AND   CHARACTER. 

of  space  through  which  they  moved,  gave  rise  to  a  variable  amount  of  metamorphism. 
In  some  few  cases,  when  the  whole  mass  was  fused,  all  evidence  of  a  previous  history  has 
been  obliterated  ;  and  on  solidification  a  structure  has  been  produced  quite  similar  to  that 
of  terrestrial  volcanic  rocks.  Such  metamorphosed  or  fused  masses  were  sometimes 
more  or  less  completely  broken  up  by  violent  collision,  and  the  fragments  again  collected 
together  and  solidified.  Whilst  these  changes  were  taking  place,  various  metallic  com- 
pounds of  iron  were  so  introduced  as  to  indicate  that  they  still  existed  in  free  space  in  the 
shape  of  vapour,  and  condensed  amongst  the  previously  formed  particles  of  the  meteorites. 
At  all  events,  the  relative  amount  of  the  metallic  constituents  appears  to  have  increased 
with  the  lapse  of  time,  and  they  often  crystallized  under  conditions  differing  entirely  from 
those  which  occurred  when  mixed  metallic  and  stony  materials  were  metamorphosed,  or 
solidified  from  a  state  of  igneous  fusion  in  such  small  masses  that  the  force  of  gravita- 
tion was  too  weak  to  separate  the  constituents,  although  they  differ  so  much  in  specific 
gravity.  ...  I  therefore  conclude  provisionally  that  meteorites  are  records  of  the  exist- 
ence in  planetary  space  of  physical  conditions  more  or  less  similar  to  those  now  confined 
to  the  immediate  neighborhood  of  the  sun,  at  a  period  indefinitely  more  remote  than 
that  of  the  occurrence  of  any  of  the  facts  revealed  to  us  by  the  Study  of  Geology  — 
at  a  period  which  might,  in  fact,  be  called  prc-tcrrcstrial.' '* 

These  views  of  Mr.  Sorbj  were  again  given  to  the  public,  with  additional 
matter,  in  1877.  He  then  stated  that 

".it  is  very  probable,  if  not  absolutely  certain,  that  the  crystalline  minerals  were  chiefly 
formed  by  an  igneous  process,  like  those  in  lava,  and  analogous  volcanic  rocks.  .  .  . 
Some  [of  the  spherules]  are  almost  spherical  drops  of  true  glass  in  the  midst  of  which 
crystals  have  been  formed,  sometimes  scattered  promiscuously,  and  sometimes  deposited 
on  the  external  surface,  radiating  inwardly ;  they  are,  in  fact,  partially  devitrified  glob- 
ules of  glass,  exactly  similar  to  some  artificial  blow-pipe  beads.  ...  I  ...  argue  that 
some  at  least  of  the  constituent  particles  of  meteorites  were  originally  detached  glassy 
globules,  like  drops  of  fiery  rain.  .  ,  .  We  cannot  help  wondering  whether,  after  all, 
meteorites  may  not  be  portions  of  the  sun  recently  detached  from  it  by  the  violent  dis- 
turbances which  .do  most  certainly  now  occur,  or  were  carried  off  from  it  at  some  earlier 
period,  when  these  disturbances  were  more  intense."  f 

David  Forbes  stated  that  meteoritic  stones  are  seen  under  the  microscope 

"  to  be  an  aggregation  of  fragmentary  matter  resembling  a  volcanic  ash  or  breccia,  in 
which,  whilst  some  of  the  particles  have  been  in  a  molten  state  (the  presence  of  both 
glass  and  air  cavities  in  them  indicating  that  they  were  in  the  molten  state  when  gases 
or  vapours  were  being  given  off),  others  show  no  signs  of  fusion ;  so  that  the  structure  of 
meteorites  confirms  the  views  that  they  have  been  formed  out  of  the  debris  of  some  pre- 
viously existing  larger  mass,  or  even  out  of  the  ruins  of  some  planetary  body."  $ 

Dr.  Stanislas  Meunier  has  done  much  work  in  the  study  of  meteorites, 
published  a  large  number  of  papers,  and  holds  some  decidedly  original  views 
regarding  their  origin.  He  maintains  that  all  have  a  common  origin,  and 

*  Geol.  Mag.,  1865  (1)  ii.  447,  448.  f  Nature,  1S76-77,  xv.  495-498. 

%  Geol.  Mag.,  1S72  (1),  ix.  222-235. 


THEORIES   OF  MEUNIER  AND   TSCHERMAK.  109 

possess  types  corresponding  to  rocks  and  structures  of  terrestrial  origin, 
i.  e.  to  lavas,  d unite,  Iherzolite,  serpentine,  breccias,  pumice,  metallic  veins, 
metamorphic  rocks,  etc.  David  Forbes  thus  concisely  gives  the  views  of 
the  former :  — 

"  Meunier,  who  has  of  late  written  more  copiously  than  concisely  on  the  subject  of 
meteorites,  whilst  believing  them  to  be  fragments  of  broken-up  planets,  regards  these 
bodies  as  but  the  last  stage  in  the  evolution  of  planetary  bodies,  and  suggests  that  the 
moon  is  rapidly  coming  to  this  stage  from  the  irregularities  and  incipient  fissures  visible 
on  its  siirt'nee,  its  dissolution  not  having  taken  place  before,  owing  to  its  greater  magni- 
tude; arguing  still  further,  that  once  broken  up  into  fragments,  'these  would  arrange 
themselves  concentrically  according  to  their  densities,  those  which  before  formed  the  cen- 
tral part  of  the  planet,  which  he  regards  as  most  heavy  and  metallic,  on  the  outside ; 
and  the  others,  according  to  their  weight,  in  the  interior.  This  arrangement  he  considers 
a< ,  ounts  for  siderites  or  meteoric  irons  having  first  fallen  in  the  earliest  ages  of  the 
world,  then  the  siderolites  [pallasites],  and  afterwards  the  stone  or  aerolites  proper;  and 
owing  to  the  meteorites  of  some  recent  falls,  particularly  that  of  Hessle  in  Sweden,  hav- 
ing contained  considerable  carbon,  he  predicts  the  fall  of  a  totally  different  class  of 
meteorites  in  future.  These  hypotheses  seem,  however,  to  be  but  mere  assumptions  inca- 
pable of  proof,  for  although  only  some  very  few  instances  of  siderites  [siderolites]  hav- 
ing fallen  in  historic  times  are  recorded,  as  compared  to  the  much  larger  number  of 
aerolites ;  still  there  is  no  proof  that  the  proportion  was  different  in  prehistoric  times, 
especially  as  it  is  well  known  that  the  latter  would  be  infinitely  more  likely  to  escape 
observation  than  the  former."  * 

Prof.  Gustav  Tschermak,  in  1875,  taught  that  meteorites  were  the  result 
of  the  disruption  of  cosmical  bodies  by  explosive  agencies.  He  stated  that 

"  the  constitution  of  many  of  the  meteorites  shows  that  they  are  the  result  of  a  grad- 
ual tranquil  crystallization  ;  while  others,  on  the  contrary,  are  composed  of  fragments, 
and  are  the  product  of  disintegrating  forces.  The  majority  are  made  up  of  minute  flakes 
and  splinters  and  of  rounded  granules." 

Following  Haidinger,  he  regarded  the  chondritic  meteorites  as  tufas,  and 
states  that  the  spherules  have  the  following  characters  :  — 

"  1.  They  are  imbedded  in  a  matrix  consisting  of  fine  or  coarse  splinter-like  par- 
ticles. 

"  2.  They  are  invariably  larger  than  these  particles. 

"  3.  They  are  always  distinct  individuals,  never  merging  into  each  other  or  joined 
together. 

"  4.  They  are  quite  spherular  when  composed  of  a  tough  mineral,  and  in  other  cases 
merely  rounded  in  form. 

"  5.  They  consist  sometimes  of  one  mineral,  sometimes  of  several  minerals,  but 
always  of  the  same  material  as  the  matrix. 

"  6.  The  structure  of  the  interior  of  a  spherule  is  in  no  way  related  to  its  external 
form.  They  are  either  fragments  of  a  crystal,  or  have  fibrous  structure  (the  fibres 


*  Geol.  Mag.,  1872  (1),  ix.  234. 


110  THE  METEORITES.  — THEIR  ORIGIN   AND   CHARACTER. 

taking  an  oblique  direction  towards  the  surface),  or  have  irregularly  barred  structure,  or 
are  granular. 

"  These  chondra  bear  no  indications  of  having  obtained  their  spherular  form  by  crys- 
tallization. .  .  .  They  resemble  rather  the  spherules  which  are  frequently  met  with  in 
our  volcanic  tuffs.  ...  As  regards  the  last  mentioned  chondra,  we  know  them  to  be  the 
result  of  volcanic  trituration,  and  to  owe  their  form  to  a  prolonged  explosive  activity  in 
a  volcanic  '  throat,'  where  the  older  rocks  have  been  broken  up,  and  the  tougher  particles 
have  been  rounded  by  continued  attrition.  The  characters  of  the  meteoric  chondra  indi- 
cate throughout  a  similar  mode  of  formation.  ...  It  is  certain,  in  short,  that  the  spher- 
ules are  the  result  of  trituration. 

"  The  [meteoric  tuffs]  are  peculiarly  characterized  as  containing  no  trace  of  a  slag-like 
or  vitreous  rock,  nor  enclosing  distinct  crystals  in  the  matrix;  in  short  they  exhibit 
nothing  which  their  formation  from  lava  would  lead  us  to  look  for.  All  that  is  to  be 
seen  in  them  is  the  triturated  product  of  a  crystalline  rock.  Some  of  the  tufaceous 
meteorites  bear  evidence  of  a  later  modification  wrought  by  heat.  .  .  .  Others,  again, 
exhibit  phenomena  which  can  only  be  explained  on  the  theory  of  their  having  under- 
gone a  chemical  change  subsequent  to  their  formation.  .  .  .  Still,  with  the  many  proofs 
which  we  possess  of  the  action  of  heat,  we  have  not  yet  met  with  a  meteorite  which 
resembles  a  volcanic  slag  or  a  lava.  Although  the  meteorites  are  comparable  to  vol- 
canic tuffs  and  breccias,  this  comparison  cannot  be  extended  beyond  a  certain  point. 
The  volcanic  activity,  of  which  the  meteorites  furnish  evidence,  consisted  in  the  disinte- 
gration of  solid  rock,  in  the  modification,  by  heat  and  otherwise,  of  already  solidified 
masses.  ...  It  is,  then,  by  explosive  activity,  and  that  alone,  that  the  breccias  and  tuffs 
which  we  find  in  meteorites  have  been  formed.  .  .  .  The  volcanic  activity  of  which 
those  mysterious  masses  of  stone  and  metal  are  evidence,  may  be  compared  to  the  violent 
movements  on  the  solar  surface,  the  more  feeble  action  of  our  terrestrial  volcanoes,  or  the 
stupendous  eruptive  phenomena  of  which  the  lunar  craters  tell  the  history.  .  .  .  Vol- 
canic activity  is  a  cosmical  phenomenon  in  the  sense  that  all  star-masses  at  a  stage  of 
their  development  exhibit  a  phase  of  volcanic  activity."  j 

The  objections  to  the  theoretical  views  of  Tschermak,  Sorby,  Forbes,  and 
Maskelyne,  can  be  briefly  stated  as  follows :  — 

The  chondritic  structure  appears  to  be  limited  to  meteorites  of  a  peculiar 
chemical  and  mineralogical  character,  while  all,  even  of  this  special  kind,  do 
not  possess  such  structure.  Hence',  if  it  was  purely  mechanical,  one  can 
hardly  see  how  this  structure  could  be  so  localized,  not  even  being  universal 
for  this  special  class.  Again,  if  the  spherules  are  the  broken-up,  and  rounded 
fragments  of  prior  existing  rock,  they  should  have  the  composition  of  that 
rock  as  a  whole,  instead  of  generally  being  composed  either  of  olivine  and 
base,  or  of  enstatite  and  base.  Also,  they  ought  to  show  in  their  interior 
the  structure  of  the  rock  from  which  they  were  derived  ;  while  distinct 
lines  of  demarkation,  and  a  want  of  continuity,  ought  to  exist  between 

*  Phil.  Mag.,  1876  (3),  i.  497-507 ;  Sitz.  Wien.  Akad.,  1875,  Ixxi.  OG1-G73. 


TIIK   CHONDKIT1C   STRUCTURE.  Ill 

each  spherule  and  the  adjacent  matrix,  as  is  the  case  with  terrestrial  rocks 
so  organized.  Such  a  relation  does  not  appear  to  exist,  except  rarely  in 
meteorites,  but  the  chondri  usually  pass  into  the  adjacent  matrix  the  same 
a<  the  secretions  formed  by  a  cooled  lava  do  into  the  surrounding  magma. 
So,  too,  we  find  different  materials  mixed  in  terrestrial  tufas ;  and  since  dif- 
ferent kinds  of  rock  fall  in  meteorites,  these  supposed  meteoric  tufas,  if  of 
mechanical  origin,  ought  to  contain  all  these  different  forms,  instead  of  only 
the  same  material  as  the  groundrnass. 

As  stated  previously,  it  seems  to  me,  from  microscopic  study  of  these 
structures,  that  they  do  not  show  any  evidence  of  fragmented  origin,  but 
they  show  rather  that  they  have  been  produced  by  rapid  and  arrested  crys- 
tallization in  a  molten  mass ;  the  result  being  in  part  due  to  the  forms 
which  the  divine  and  enstatite  tend  to  assume  on  crystallization.  If  time 
enough  had  been  given,  an  entire  crystallization  of  the  material  would 
have  taken  place,  as  in  the  Estherville  peridotite,  and  in  the  common  ter- 
restrial peridotites.  Of  the  latter,  the  crystallization  is  either  complete, 
or  else  the  original  structure  has  been  obliterated  by  alteration.  If  we 
could  find  rapidly  cooled,  unaltered  terrestrial  peridotic  rocks,  I  should 
expect  to  find  in  them  the  chondritic  structure,  the  same  as  the  Esther- 
ville meteorite  possesses  the  structure  of  an  unaltered  terrestrial  peridotite, 
and  the  meteoric  pallasites  possess  that  of  the  terrestrial  ones. 

A  similar  method  of  crystallization,  with  the  production  of  a  similar  struc- 
ture, has  been  observed  by  me  in  the  crystallization  of  watery  vapor  on  the 
windows  of  horse-cars  during  extremely  cold  weather.  When  the  window  is 
Tintouched  the  crystallization  is  after  the  usual  manner,  familiar  to  all  as 
occurring  in  our  houses ;  but  when  the  car-window  has  had  this  first  deposit 
removed,  ;\s  is  frequently  done  by  passengers,  for  the  purpose  of  looking 
out,  the  abundant  vapor  of  the  crowded  car  is  rapidly  deposited  on  this  cold 
surface,  and  in  such  abundance  as  to  give  rise  to  similar  elliptical  and  spheru- 
litic  figures,  which  in  form  and  appearance  resemble  the  chondritic  forms  the 
more  closely  the  more  they  interfere  with  the  development  of  one  another. 
They  also  possess  the  eccentric-fan  and  ribbed  structure  so  commonly  seen 
in  the  enstatite  chondri  —  the  radiation  starting  from  one  side.  Again,  on 
interfering  with  one  another,  they  tend  to  take  a  rounded,  instead  of  an 
angular  or  irregular  form. 

That  rounded,  drop-like  masses  should  be  inclosed  in  meteorites  is  natu- 
rally to  be  expected,  in  case  they  came  from  the  sun  or  any  similar  body,  for 


112  THE  METEORITES.  —  THEIR   ORIGIN   AND   CHARACTER. 

material  is  continually  being  thrown  up  from  their  surfaces  and  falling  back 
again  ;  and  it  is  to  be  expected  that  some  of  these  drops  would  be  inclosed 
and  thrown  up  in  other  masses  before  they  had  been  entirely  liquefied, 
although  they  were  probably  viscous. 

So  far  as  meteorites  have  been  examined  by  me,  they  do  not  appear  to  be 
fragmental  in  the  sense  of  consolidated  cold  masses  joined  together.  It  is 
possible  that  they  may  be  composed  in  part  at  least,  of  molten  globules  - 
originally  united  in  a  pasty  condition ;  but  the  uniformity  of  composition  of 
each  spherule  is  a  remarkable  circumstance,  if  they  are  formed  from  drops. 
One  would  suppose  that  each  chondrus  would  possess  all  the  elements  of  the 
meteorite  as  a  whole. 

So  far  as  can  be  learned  from  the  structure  of  most  meteorites,  it  appears 
to  the  writer  that  they  must  have  come  from  a  liquid  mass,  and  that  in  the 
majority  of  cases  the  length  of  time  in  which  they  passed  from  the  liquid  to 
the  solid  condition  was  not  great.  The  silicates  held  in  the  interstices  of 
metallic  masses,  like  the  pallasites,  would  have  time  to  crystallize  through 
the  effect  of  the  heat  of  the  surrounding  iron,  and  the  chondritic  structure 
would  not  be  developed  in  this  class  as  a  rule,  if  at  all ;  while  Professor  Ball's* 
claim  that  meteorites  must  have  been  torn  from  a  solid  rock  does  not  seem 
to  be  borne  out  by  -the  structure  of  the  meteorites  themselves.  Starting 
with  the  hypothesis  that  all  cosmical  matter  was  originally  in  a  gaseous  state, 
and  that  this  gas,  through  condensation  or  otherwise,  was  intensely  hot,  the 
writer  believes  that  the  meteoric  material,  reaching  the  earth,  was  thrown 
from  some  one  or  more  of  these  condensing  bodies,  formed  from  this  cosmi- 
cal matter  during  its  liquid  or  partially  solid  state.  He  holds  that  of  these 
bodies,  the  most  probable  one  serving  as  the  source  of  meteorites  is  the  sun, 
as  suggested  by  Sorby  —  they  either  being  thrown  from  it  now,  or  in  past 
time,  through  eruptive  agencies,  whose  action  can  now  be  seen  upon  its  sur- 
face. It  is  of  course  possible  that  any  of  the  celestial  bodies,  when  in  the 
incandescent  condition,  while  eruptive  forces  were  sufficiently  active,  might 
be  the  originator  of  meteorites ;  but  before  any  meteorites  are  attributed  to 
them,  it  is  necessary  that  it  should  be  shown  that  their  probable  constitu- 
tion corresponds  to  that  of  the  meteorites  in  question. 

The  number  of  elements  common  both  to  the  sun  and  meteorites  lends 
some  support  to  their  relation  as  advocated  here.  These  elements  are  iron, 
titanium,  calcium,  manganese,  nickel,  cobalt,  chromium,  sodium,  magnesium, 

*  Science  for  All,  iv.  31. 


THE   ERUPTIVE   ENERGY  OF  THE   SUN.  113 

copper,   hydrogen,  vanadium,   strontium,    aluminum,   sulphur  (?),  oxygen, 
lithium,  tin,  and  carbon. 

The  question  whether  it  would  be  possible  for  meteorites  to  be  derived 
from  the  sun  by  their  being  thrown  off  from  it  by  eruptive  agencies,  is  a 
problem  for  physicists  ;  if  it  can  be  shown  that  the  sun's  constitution  is  such 
as  to  render  it  not  improbable  that  meteorites  could  have  this  origin.  The 
immense  velocities  of  the  eruptive  prominences  —  from  100  to  200  miles 
per  second,  or,  according  to  Proctor,  500  miles  —  indicates,  with  their  great 
height  of  sometimes  from  150,000  to  350,000  miles,  a  violence  of  eruption 
tending  to  hurl  solid  materials  far  away  from  the  sun  into  space.  The  ele- 
ments seen  in  the  spectrum  of  these  prominences,  iron,  sodium,  magnesium, 
titanium,  calcium,  chromium,  manganese,  and  probably  sulphur,  are  with 
one  exception,  common  ingredients  in  meteorites.* 

If  the  above-mentioned  velocity  may,  on  investigation,  be  deemed  suffi- 
cient to  project  matter  into  space,  the  prevailing  view  of  astronomers  that 
the  sun  as  a  whole  is  gaseous,  and  neither  liquid  nor  solid,  would  certainly 
be  opposed  to  the  solar  origin  of  meteorites.  As  before  stated,  their  con- 
stitution would,  so  far  as  we  are  acquainted  with  the  action  of  gaseous 
substances,  demand  that  the  meteorites  should  be  derived  from  a  hot  liquid. 
The  body  from  which  they  came  might  be  for  the  most  part  solid,  or 
gaseous,  or  both,  but  that  the  portion  from  which  they  came  should  be 
liquid  seems  a  necessity.  The  liquid  condition  of  the  sun  is  also  the  best 
explanation  of  the  eruptive  phenomena  now  observed  upon  it.f 

Should  it  be  shown  that  meteorites  might  come  from  the  sun,  its  eruptive 
energy  being  sufficient,  it  would  be  rendered  probable  then  that  meteorites 
might  have  been  thrown  from  the  sun  when  larger,  as  well  as  from  the 
planets  and  their  satellites  during  their  condensation  —  if  the  nebular  hypo- 
thesis is  accepted.  It  would  certainly  seem  that  the  present  view  of  the 
partial  or  entire  meteoric  constitution  of  the  corona,  the  zodiacal  light,  the 
G>'>/i',ixrlin,i,  of  Saturn'sx  rings,  and  of  comets,  bears  directly  on  this  question. 
If  our  sun  may  do  this,  is  it  not  consistent  to  suppose  that  other  suns  may  do 
the  same,  and  thus  account  for  the  comets,  their  varied  orbits,  as  well  as  for 
the  supposed  diverse  constitution  of  the  August  and  November  meteors. 

The  theory  that  meteorites  come  from  the  sun  is  by  no  means  a  new  one, 

*  Young,  The  Sun,  1881,  pp.  202,  207-212. 
f  Youug,  /.  r.,  p.  211. 
15 


114  THE  METEORITES.  — THEIR  ORIGIN   AND   CHARACTER. 

being  as  old  as  the  days  of  Diogenes  Laertius,  and  in  recent  times  has  been 
advocated  by  Hackley,*  Wilcocks,t  Williams, $  Sorby,  and  others. 

If,  in  the  process  of  condensation  of  the  sun  from  a  gaseous  to  a  liquid 
state,  the  metallic  portion  liquefied  before  the  silicates,  would  it  riot  in  some 
measure  account  for  the  metallic  meteorites  being  so  common  in  the  past  and 
rare  at  the  present  time,  and  for  the  peridotic  ones  being  the  common  type 
now  ?  On  account  of  their  specific  gravity,  meteorites,  as  a  rule,  could  not 
be  derived  from  the  moon ;  unless  it  should  be  held  that  its  interior  is  now 
much  hotter  than  the  earth's  interior,  and  its  density  made  less  through 
that  means.  This  is  an  improbable  supposition  on  account  of  its  small  size, 
compared  with  that  of  the  earth,  which  would  lead  to  its  more  rapid  cooling. 
Since  the  specific  gravity  of  the  moon,  as  a  whole,  is  about  that  of  the  more 
common  meteorites,  and  if  the  law  of  the  increase  of  density  from  the  sur- 
face to  the  centre  is  the  same  as  that  observed  upon  the  earth,  it  follows 
that  the  moon's  surface  formations  must  have  far  less  density  as  a  whole  than 
those  belonging  to  the  earth.  The  law  of  eruption  as  observed  upon  the 
earth  is,  that  the  lighter  eruptive  material  as  a  whole  is  most  abundant, 
while  the  rocks  approaching  the  mean  density  of  the  earth  are  compara- 
tively rare,  so  much  so  that  their  presence  is  generally  denied.  This  law 
ought  also  to  hold  good  on  the  moon,  and  eruptive  material  from  it,  forming 
meteorites,  ought  to  have  less  specific  gravity  as  a  whole  than  our  granites. 
The  astronomical  reasons  have  usually  been  regarded  as  sufficient  to  show 
that  meteorites  could  not  come  from  the  moon,  and  that  theory  is  not  now 
especially  urged  by  any  one. 

Such  a  view  as  advocated  by  Messrs.  Ball  and  Rodwell,§  that  meteorites 
were  thrown  from  the  earth  in  past  times,  is  negatived  by  their  general 
composition,  which,  as  a  rule,  is  different  from  the  exterior  portions  of  the 
earth.  If  they  were  originally  terrestrial,  these  meteorites  ought  to  more 
commonly  possess  the  characters  of  basalts,  andesites,  trachytes,  etc. 

Whether  the  view  that  meteorites  came  from  the  sun  demands  too  great 
a  loss  to  his  mass,  since  accurate  records  have  been  kept,  is  a  problem  for 
the  physical  astronomer. 

Since  it  is  possible  that  careful  examinations  of  meteorites  by  chemical 
and  spectral  methods  will  throw  light  on  the  constitution  of  the  celestial 

*  Proc.  Am.  Assoc.  Adv.  Sci.,  1360,  xiv.  4-6. 

f  Proc.  Am.  Phil.  Soc.,  186  K  ix.  381-387. 

J  The  Fuel  of  the  Sun,  London,  1870,  pp.  131-142. 

§  Science  for  All,  iv.  32;  Nature,  1879,  xix.  493-495. 


CONTEMPORANEOUS  CRYSTALLIZATION  OF  IRON  AND  SILICATES.      115 

bodies  —  especially  concerning  the  strange  lines  in  the  sun's  spectrum  —  it 
would  appear  that  meteorites  ought  to  be  studied  more  critically  than  ever 
for  the  rarer  elements,  as  well  as  for  some  at  present  unknown. 

Careful  examinations  ought  also  to  be  made  on  microscopic  sections  of 
recently  fallen  meteorites,  in  order  to  ascertain  if  any  changes  have  taken 
place  in  the  rock  since  it  was  first  formed,  but  before  it  reached  this  earth, 
since  all  changes  now  seen  in  them  are  referred  to  the  action  of  our  atmos- 
phere after  the  fall  of  the  meteorite.  It  is  not  to  be  expected  that  in 
any  way  can  any  clue  be  obtained  as  to  how  recently  or  how  long  ago  the 
meteorite  left  its  parent  mass,  since  no  alteration  in  its  substance  can  be 
expected  to  have  taken  place  in  inter-solar  space. 

Mr.  H.  C.  Sorby's  view*  that  it  is  impossible  for  minerals  of  so  diverse 
specific  gravity  as  iron  and  olivine  to  crystallize  together  in  the  pallasites 
and  other  metallic  meteorites  on  the  surface  of  the  earth  or  any  large  body, 
but  that  they  came  from  the  metallic  centre  of  small  bodies,  or  else  formed 
small  planets  by  themselves,  does  not  seem  to  be  well  founded.  The  same 
method  of  reasoning  would  prove  that  magnetite  could  not  be  formed  with 
leucite,  or  feldspar,  or  augite  in  any  lava-flow  on  the  earth's  surface  ;  yet 
they  are  minerals  of  common  occurrence  together  in  lavas.  Hence  it  is 
claimed  liere  that  the  crystallization  of  silicates  with  metallic  iron  might,  so 
far  as  gravity  is  concerned,  take  place  on  the  surface  of  the  earth  as  it  has 
been  proved  to  have  done  in  Greenland.  So  too,  if  such  a  structure  and 
arrangement  of  iron  and  olivine  could  not  take  place  on  the  surface  of  a  body 
like  the  earth,  then  the  rocks  of  Cumberland,  Rhode  Island,  and  of  Taberg, 
Sweden,  ought  not  to  exist  since  they  have  this  structure  and  are  at  the 
surface  of  the  earth.  The  difference  between  the  magnetite  and  olivine  is 
not  so  great  as  that  between  the  native  iron  and  olivine,  but  yet  it  is  suffi- 
cient to  cause  a  separation,  if  Sorby's  view  is  correct. 

Helmholtz's  theory  that  the  earth  is  built  out  of  meteorites  is  negatived 
by  the  following  facts :  the  geological  formations  in  and  of  themselves  are 
not  composed  of  detached  fragments  like  meteorites ;  meteorites,  so  far  as 
known,  are  not  found  in  the  geological  formations ;  and  the  chemical  com- 
position of  the  latter  is  different  from  that  of  the  meteorites.  His  view 
seems  to  be  a  pure  theory  without  any  regard  being  paid  to  the  actual 
known  structure  and  composition  of  the  earth  and  meteorites.  As  well 

»  Quart.  Jour.  Sci.,  1864,  i.  747. 


116  THE   METEORITES.—  THEIR   ORIGIN   AND  CHARACTER. 

might  the  physicist  explain  the  dispersion  of  boulders  in  the  northern  drift,* 
or  the  origin  of  the  large  nuggets  in  the  gold  placers  by  supposing  that  they 
were  meteorites,  as  to  explain  the  earth's  structure  by  the  meteoric  theory. 

The  further  supposition  that  the  earth  has  been  formed  from  meteoric 
matter  that  became  entirely  fused  from  the  impact  of  the  falling  masses  is 
one  that  makes  an  assumption  and  then  deprives  us  of  every  means  of  dis- 
proving or  proving  it. 

Everything  relating  to  the  state  of  the  earth  prior  to  its  fluid  condition 
is  of  course  a  matter  of  conjecture,  and  theories  relating  to  it  are  beyond 
scientific  discussion,  as  belonging  to  the  unknown  and  unknowable. 

The  origin  of  meteorites,  as  shown  by  their  structure,  yields  but  little 
assistance  to  the  theory  of  the  introduction  of  life  upon  this  planet  through 
their  agency;  since  the  conditions  under  which  they  were  formed,  and  those, 
so  far  as  can  be  ascertained,  to  which  they  have  been  since  subjected  are  not 
compatible  with  life  as  understood  upon  this  globe. t 

In  other  words  it  may  be  said  that  meteorites  show  in  their  structure 
that  they  have  been  formed  from  molten  liquid  material,  while  their  chemical 
composition  is  such  as  to  show  that  they  could  not  have  been  exposed  to  air 
and  water  upon  any  globe  in  conditions  compatible  with  life  as  we  under- 
stand it.  If  their  structure  points  to  an  igneous  origin,  and  their  composition 
shows  that  they  could  not  have  been  exposed  to  conditions  such  as  earth-life 
demands,  then  Sir  William  Thomson  was  not  right  in  claiming  that  it  was 
scientific  to  suppose  that  life  was  brought  to  this  earth  by  meteorites.  It 
certainly  only  pushes  the  question  of  life  a  little  farther  off;  it  begs  the 
question  but  does  not  solve  it,  even  could  it  have  been  shown  that  life  might 
have  been  thus  brought  here.  Zollner  was  indeed  right  in  opposing  this 
theory  and  regarding  it  as  unscientific.  Assuredly,  the  germs  inclosed  in 
crevices  would  be  destroyed  by  the  cold  of  space,  as  much  as  the  exterior 
ones  would  be  by  the  heat  generated  by  the  passage  of  the  meteorite 
through  the  air.  It  is  not  intended  to  state  that  water  or  air  could  not  be 
present  on  the  body  from  which  meteorites  come,  but  that  the  meteorites 
could  not  have  been  exposed  any  length  of  time  to  such  agencies,  or  their 
constitution  would  have  been  changed. 

*  Since  the  above  was  written  such  an  explanation  has  been  published,  entitled :  "  Ragnarok  —  the  Age 
of  Fire  and  Gravel,"  —  by  Ignatius  Donnelly. 

f  W.  Thomson,  Proc.  British  Assoc.,  1871,  pp.  civ.,  cv. ;  1877  (Sect.),  p.  43 ;  A.  Thomson,  ibid.,  1877, 
p.  75  ;  Ilelmholtz,  Popular  Scientific  Lectures  (Sec.  Ser.),  1881,  pp.  193,  196,  197;  Nature,  1875,  xi.  212; 
J.  C.  F.  Zollner,  "Ueber  die  Natur  der  Cometen,  Leipzig,"  1872,  p.  21;  Walter  Flight,  Pop.  Sci.  Rev., 
1877,  xvi.  390-401 ;  David  Forbes,  Geol.  Mag.,  1872  (1),  ix.  234,  235. 


THE   SOURCE   OF   VEIN   MATERIALS.  117 

Again  .since  mineral  veins  appear  to  have  been  formed  on  the  earth  by 
the  action  of  percolating  waters,  none  of  the  meteorites  can  be  of  such  vein 
formation,  as  has  been  claimed  by  M.  Meunier,  since  they  show  by  their  com- 
position that  they  have  not  been  exposed  to  or  formed  in  the  presence  of 
water;  and  so  far  as  the  present  writer  is  concerned, he  sees  nothing  in  their 
structure  supporting  such  a  theory,  even  if,  as  Meunier  seems  to  think,  these 
veins  were  formed  by  sublimation. 

The  finding  of  many  of  the  metals,  in  larger  or  smaller  amounts,  in 
meteorites  points  to  a  relation  between  them  and  terrestrial  eruptive  rocks. 
The  association  of  metallic  veins  with  eruptive  or  metamorphosed  rocks, 
coupled  with  other  characters,  indicates  that  our  metals,  as  concentrated  in 
veins,  have  generally  been  derived  by  aqueous  and  chemical  agencies  from 
eruptive  rocks  and  their  debris.  This  deposition  may  be  direct  or  indirect, 
but  primarily  the  starting  point  is  believed  to  have  been  the  original  molten 
material  of  the  earth.* 

The  more  common  association  of  metalliferous  veins  with  basic  rather 
than  acidic  rocks  points  towards  the  deeper-seated  origin  of  the  former,  as 
has  been  claimed  by  many.f 

The  occurrence  of  copper  in  so  many  of  the  meteoric  forms  has,  it  seems 
to  the  writer,  an  important  bearing  on  the  question  of  the  origin  of  the 
native  copper  of  Lake  Superior.  He  holds  that  it  was  derived  from  the 
associated  basaltic  rocks  as  he  has  set  forth  in  another  paper. $ 

If  copper  is  an  almost  constant  associate  of  meteorites,  ought  it  not  to 
naturally  be  associated  with  eruptive  rocks  which  are  held  to  be  part  of  the 
original  materials  of  which  the  solar  system  is  composed  ?  The  basic 
rocks  are  naturally,  then,  the  ones  with  which  the  copper  should  be  associ- 
ated, and  it  is  with  basaltic  rocks  —  diabases  and  melaphyrs  —  that  it  is 
commonly  found,  as,  for  instance,  on  Lake  Superior,  Bay  of  Fundy,  and  in 
Newfoundland. 

The  metallic  iron  in  the  basalt  of  Greenland,  the  native  iron  found  in 
b;isilts  by  Dr.  Andrews,  that  found  in  gabbros  from  New  Hampshire,  by  Dr. 
George  W.  Hawes,  and  in  gabbros  from  the  west  of  Scotland,  by  Mr.  J.  Y. 
Buchanan,  all  serve  to  connect  the  meteorites  with  the  terrestrial  rocks. § 

*  Whitney,  Aurif.  Gravels,  pp.  310,  Oil. 

•J-  Whitney,  Earthquakes,  Volcanoes  and  Moimtuiu  Building,  p.  85. 

j  Bull.  Mus.  Coinp.  Zool.,  1SSO.  vii.  130. 

§   Baporl  I'.rii.  isMO.,  1852,  xxii.  (Sect.)  34,  35;  Geikie's  Text  Book  of  Geology,  1882,  p.  61;  Geol. 

Nrw  Hampshire,  Ib79,  iii.  part  i,  p.  ii. 


118  PERIDOT1TE. 

In  the  same  way  the  presence  of  nickel,  chromium,  tin,  copper,  and  cobalt 
in  the  group  of  terrestrial  olivine  minerals,  serves  to  connect  the  earth 
and  meteoric  bodies ;  as  also  does  the  presence  of  nickel  in  the  terrestrial 
pyrrhotite  and  magnetite. 

SECTION  IV.  —  The  Terrestrial  Peridolites. 

VARIETY.  —  Dunite. 
Franklin,  North   Carolina. 

5134.  An  oil-green,  crystalline-granular  rock,  weathering  from  a  yellowish-green  to  a 
reddish-brown.  Composed  of  a  granular  mass  of  olivine,  holding  irregular  grains  and 
crystals  of  chromite  and  long  needles  of  tremolite.  It  contains  some  talc  and  dark-green 
chlorite. 

Section :  a  clear,  pale-yellowish,  fissured  mass,  composed  of  olivine,  with  some  talc, 
chromite,  and  tremolite.  The  olivine  is  in  clear  transparent  grains,  tinged  slightly  yellow 
along  the  fissures.  It  contains  some  chromite  and  glass  inclusions,  —  the  two  often  being 
associated.  The  talc  is  in  clear  irregular  plates,  showing  a  longitudinal  cleavage.  The 
polarization  is  generally  simple,  but  sometimes  aggregate.  An  earthy,  white  substance 
was  observed  in  some  cases  lying  between  the  laminae. 

The  chromite  is  generally  in  octahedral  crystals,  although  a  few  minute  grains  of  irreg- 
ular form  were  seen.  The  chromite  was  opaque  in  every  instance.  A  few  minute 
rounded  grains  were  observed,  that  may  possibly  be  picotite. 

The  section,  to  my  mind,  presents  the  characters  of  a  granular  rock,  resulting  from  a 
cooling  igneous  magma  —  an  eruptive  rock.  The  olivine  is  in  grains  which  are  separated 
only  by  fine  cracks,  every  irregularity  in  one  being  matched  by  corresponding  irregular- 
ities in  its  neighbors.  If  these  grains  were  olivine  sands  aggregated  by  wind  or  water, 
such  uniformity  would  not  exist.  The  grains  would  be  irregularly  massed  together,  with 
interstitial  portions  filled  with  binding  material.  The  cracks  which  separate  the  different 
individual  grains  are  the  same  as  those  which  separate  different  portions  of  the  same 
grain.  The  absence  of  any  signs  of  wearing  to  the  grains,  and  their  matching  one  another 
as  they  would  in  this  substance  when  completely  crystallized,  point  towards  an  eruptive 
origin  for  the  rock.  In  addition,  long,  lenticular,  much  broken  grains  are  seen,  whose  parts 
show  in  polarized  light  that  they  belong  to  the  same  individual.  They  are  arranged  at 
every  angle  with  one  another ;  but  if  these  grains  had  been  deposited  as  a  shore  sand,  it  is 
difficult  to  see  how  they  could  have  retained  their  sharp  thin  cutting  edges.  Again,  these 
grains  and  the  general  structure  of  the  rock  are  like  those  observed  in  the  Estherville 
meteorite,  which  I  think  no  one  would  be  inclined  to  regard  as  a  beach  deposit.  The 
granular  structure  appears  to  me  to  be  due  to  the  crystallization  of  a  mineral  inclined  to 
take  such  a  rounded  form  as  olivine  usually  has.  The  same  structure  and  arrangement 
of  the  grains  from  a  cooling  eruptive  rock  had  been  previously  seen  by  the  writer  in  quartz 
in  some  granitoid  rocks  from  Lake  Superior,  part  of  which  are  known  to  be  in  dikes,  while 
the  others  are  probably  also  eruptive.* 

Many  of  the  larger  olivine  grains  show  a  faint  banded  polarization,  the  bauds  being 
nearly  parallel  with  a  crystallographic  axis.  The  structure  of  this  section  is  shown  in 
Plate  IV.  figure  2 ;  the  darker  bauds  indicating  the  fissures  in  the  grains. 

*  Bull.  Mus.  Comp.  Zobl.,  18SO,  vii.  53-55. 


THE  TERREST1UAL   PEIUDOTITES.  —  DUNITE.  119 

W<  lister,  North  Carolina. 

5135.  A  oiyatalline-gnQttlar  rock,  of  a  yellowish-brown  color  on  the  fresh  fracture. 
Lustre  resinous  and  greasy,  fracture  uueven-conchoidal.  Weathered  to  a  granular  pale- 
yrllow  mass,  on  tlie  exterior  portions.  Contains  grains  and  crystals  of  picotite. 

Section :  of  a  pale-yellow  color ;  composed  of  olivine,  enstatite,  diallage,  picotite,  and 
.serpentine.  The  oliviue  forms  the  chief  portion  of  the  rock,  and  is  in  irregular  fissured 
grains.  It  is  clear-transparent,  and  holds  grains  of  picotite,  some  of  which  are  in  minute 
lenticular  forms.  The  picotite  is  very  abundant,  but  mostly  in  minute  microscopic 
grains  of  a  coffee-brown  color.  The  macroscopic  picotites  are  opaque,  except  in  the  thin- 
nest portions. 

The  enstatite  and  diallage  are  in  small,  transparent,  irregular  masses,  lying  between  the 
olivine  grains.  Both  are  traversed  by  longitudinal  fissures,  but  in  general  the  enstatite 
i -It -avage  is  better  marked  and  more  finely  fibrous  than  that  of  the  diallage.  The  latter 
mineral  was  observed  sometimes  to  have  the  irregular,  approximately  right-angled  cleav- 
age of  augite.  Although  the  enstatite  could  sometimes  be  separated  from  the  diallage  by 
its  cleavage,  in  general  the  distinction  was  made  solely  by  optical  methods.  , 

The  serpentine  is  mainly  of  a  pale-yellowish  color,  although  in  some  places  a  darker 
or  brownish  color  was  observed.  It  follows  the  fissures,  making  a  network,  envelop- 
ing the  fragments  of  olivine,  enstatite,  and  diallage.  Many  of  the  oliviue  grains  now 
separated  by  serpentine  are  seen  by  their  optical  characters  to  be  parts  of  the  same 
original  crystallographic  mass.  The  serpentine  is  plainly  a  secondary  product,  formed 
from  the  alteration  of  part  of  the  original  minerals,  comprising  this  peridotite.  In  some 
parts  of  the  section  in  which  the  mineral  fragments  were  small,  the  minerals  have  been 
changed  entirely  to  serpentine,  forming  ganglion-like  masses  in  this  plexus  of  serpentine. 
The  serpentine  shows  the  common  fibrous  polarization,  the  fibres  standing  perpendicular 
to  the  svalls  of  the  channel. 

Plate  IV.,  figure  3,  shows  well  the  yellowish  and  greenish  serpentine  alteration  along 
the  fissures,  and  surrounding  the  clear  olivine  grains.  The  brown  spots  are  picotite 
grains. 

Dr.  F.  A.  Genth,  in  1862,  made  an  examination  of  some  Webster  (Jackson  Co.,  X.  C.) 
peridotite,  and  stated  that  they  gave  "  evidence  that  chrysolite  is  probably  the  mineral 
from  which  talc  slate  and  many  of  the  serpentines  have  been  formed."  * 

Dr.  Alexis  A.  Julien  regards  the  North  Carolina  peridotite  as  formed  by  consolidated 
olivine  sand  —  a  detrital  deposit  derived  from  the  wearing  down  of  older  eruptive  rocks. 
He  describes  the  rock  as  occurring  in  long  lenticular  masses,  that  show  a  laminated  struc- 
ture ;  giving  his  reasons  why  he  regards  this  lamination  as  due  to  the  sorting  of  sediments 
deposited  in  water.  His  reasons  for  holding  that  the  dunite  is  a  sedimentary  rock  are 
good  so  far  as  they  go,  but  they  do  not  appear  to  be  conclusive ;  since  the  same  condition 
of  things  could  readily  exist  in  an  eruptive  rock.  The  rock,  when  altered  near  the  surface 
of  disintegration,  is,  according  to  Julien,  bound  together  by  a  network  of  quartz  or  actino- 
lite  fibres. 

The  alterations  in  the  rock-mass,  as  traced  out  by  Dr.  Julien,  are  very  interesting. 
Briefly,  they  are  as  follows:  1.  Chalcedonic;  2.  Hornblendic;  3.  Talcose ;  4.  Ophiolitic; 
5.  Dioritic. 

In  the  first,  the  silicates  are  decomposed,  the  silica  forming  chalcedony  or  chert,  while 
the  bases  remain  as  soft  ochreous  grains,  or  are  entirely  removed. 

*  Am.  Jour.  Sci.,  1862  (2),  xxxiii.  199-203. 


120  PERIDOTITE. 

In  the  second  case,  the  alteration  consists  in  the  formation  of  a  few  crystals,  and  in 
every  gradation  from  that  to  a  state  in  which  the  dunite  has  been  transformed  into  a  more 
or  less  schistose  rock,  largely  composed  of  hornblende,  and  actinolite  or  tremolite.  A  few 
"rains  of  olivine  usually  remain  unchanged  even  in  these  extreme  alterations. 

The  third  change  is  brought  about  either  by  the  direct  alteration  of  the  olivine,  or  by 
the  conversion  of  the  secondary  actinolite  itself  into  talc.  Through  this  alteration  talcose 
rocks  are  formed,  like  talc-schists  ;  as  well  as  amphibolitic  or  olivine  ones  bearing  talc. 

The  fourth  alteration  has  been  described  by  me  in  the  preceding  account  of  the  Web- 
ster peridotite,  and  hence  I  will  not  here  quote  from  Dr.  Julien,  farther  than  to  say  that 
according  to  him  talc  is  frequently  associated  with  the  serpentine,  thus  forming  a  talcose 
serpentine. 

The  fifth  and  last  alteration  is  "  confined  to  a  single  locality,  and  consists  of  an  inter- 
nal conversion  of  the  olivine  into  amphibole  —  a  bright  grass-green  variety  which  Dr. 
Genth  has  identified  as  smaragdite  or  kokscharoffite  —  and  albite,  sometimes  with  abun- 
dantly disseminated  particles  of  ruby  red  corundum,  producing  a  peculiar  variety  of 
diorite  or  gabbro.  Again,  this  very  rock  has  been  subsequently  attacked  by  a  secondary 
process  of  alteration,  the  albite  grains  being  enveloped  by  an  alteration-crust  of  margarite, 
and  the  condition  of  hornblende  modified.  The  result  of  this  action  is  a  coarse  margaritic 
gabbro." 

Dr.  Julien  believes  that  many  of  the  amphibole  and  talc-bearing  schists  and  serpen- 
tines along  the  Appalachian  belt  are  the  equivalents  of  the  North  Carolina  dunite. 

The  North  Carolina  peridotites  have  been  described  in  previous  papers  by  Genth, 
Jenks,  Kerr,  C.  D.  Smith,  Shepard,  J.  L.  Smith,  Raymond,  and  others.* 

In  most  of  the  above  papers,  corundum  is  especially  treated  of,  since  it  has  been 
largely  found  associated  with  the  peridotites  of  the  Southern  States.  This  mineral  Genth 
regards  as  original,  but  Julien  as  a  secondary  product  of  alteration.  Various  opinions 
have  been  advanced  concerning  the  North  Carolina  peridotite — that  it  is  of  chemical, 
sedimentary,  and  eruptive  origin.  Messrs.  Kerr  and  C.  D.  Smith  who  have,  except  Julien, 
studied  the  rock  most  in  the  field,  regard  it  as  eruptive,  but  the  published  evidence  given  by 
them  is,  like  Julien's,  not  conclusive.  The  reasons  that  the  present  writer  has  for  believing 
this  rock  to  be  of  eruptive  origin  have  already  been  given.  It  hardly  seems  possible  that 
the  olivine  could  have  been  deposited  as  a  loose  sand,  exposed  to  water  and  air,  consoli- 
dated, and  remained  until  the  present  time  unchanged.! 

Tafjord,  Nonvay. 

The  rock  from  Tafjord,  Norway,  as  seen  in  a  section  purchased  from  Richard  Fuess, 
Berlin,  is  composed  principally  of  rounded  grains  of  olivine,  with  some  enstatite,  cof- 
fee-brown picotite  or  chromite,  and  a  little  magnetite.  The  structure  is  essentially  the 
same  as  that  of  the  peridotite  from  Franklin,  North  Carolina.  The  form  and  arrangement 
of  the  enstatite  are  very  similar  to  those  of  the  talc  in  No.  5134. 

Mohl  describes  this  rock  as  being  similar  to  the  one  from  Eodfjeld,  but  with  less 
enstatite,  and  some  magnetite.  \ 

*  Am.  Phil.  Soc.  Proc.,  1873,  xiii.  361-406  ;  1874,  xiv. ;  1SS2,  216-218,  381-404;  Quart.  Jour.  Geol. 
Soc.,  1874,  xxx.  303-306;  Geol.  of  North  Carolina,  1875,  vol.  i.  129-130;  Appendix  D,  pp.  91-97,  102- 
107  ;  1881,  vol.  ii.  42,  43;  Am.  Jour.  Sci.,  1872  (3),  iii.  301,  302;  iv.  109-115,  175-180;  1873.  vi.  180- 
186 ;  Pop.  Sci.  Monthly,  1874,  iv.  452-456  ;  Trans.  Am.  List.  Min.  Eng.,  1878,  vii.  83-90. 

f  Proc.  Bost.  Soc.  Nat.  Hist.,  1S82,  xxii.  141-149.     See  also  Science,  1884,  iii.  486,  487. 

}  Nyt  Mag.,  1877,  xxiii.  115,  116. 


TIIK   TERRESTRIAL   PERIDOTITES.  —  DUNITE.  121 

Dtm  Mountain,  New  Zealand. 

Tim  peritlotite  (dunite)  of  New  Zealand  is  described  by  Hochstetter  as  a  Mesozoic 
eruptive  mass,  associated  with  serpentine  and  hyperite,  also  of  eruptive  origin.  This 
dunite  is  a  crystalline-granular  rock,  of  light  yellowish-green  to  a  grayish-green  color  on 
the  fresh  fracture,  and  weathering  to  a  dirty,  rusty,  sometimes  yellowish,  sometimes  red- 
dish-brown color.  Fracture  uneven,  granular,  angular,  and  coarse-splintery.  It  was 
found  to  be  composed  of  granular  olivine,  holding  octahedrons  of  chromite,  with  rounded 
edges.  The  serpentine  was  formed  by  the  alteration  of  the  peridotite  in  situ.* 

M.  K'enard  has  given  a  brief  description  of  the  microscopic  characters  of  this  rock. 
The  section  is  composed  of  irregular  grains  of  olivine,  but  of  larger  size  than  those  in 
the  St.  Paul's  peridotite,  to  be  described  later.  "With  this  exception,  the  other  micro- 
scopical characters  are  the  same  in  both  rocks :  the  fissures,  more  or  less  regular,  marked 
by  black  lines,  intense  chromatic  polarization  of  the  divine,  roughness  of  the  surface, 
etc.,  etc.  The  sections  of  chromic  iron  in  duuite  are  larger  than  those  in  the  specimens 
from  St.  Paul,  but  in  other  respects  they  present  the  same  features."  f 

Soiidmore,  Norway. 

The  thin  sections  of  this  rock,  according  to  P>rogger,  contain  predominating  olivine,  with 
(very  sparingly)  beautiful  green  smaragdite,  here  and  there  a  grain  of  brownish-yellow 
enstatite,  and  chromite  in  little  grains.  The  olivine  is  fresh,  clear-green,  and  in  the  sec- 
tion colorless,  and  fine-granular.  Some  grains  show  one  cleavage  parallel  to  the  longer 
direction  of  the  crystals,  and  another  perpendicular  to  the  same.  Only  a  trace  of  altera- 
tion to  serpentine  was  observed.  The  smaragdite  is  of  a  green  color,  fresh,  and  shows 
pleochroism.  The  only  two  grains  in  the  section  were  elongated  in  the  direction  of  the 
vertical  axis,  and  show  cleavage  lines  running  in  the  same  direction.  The  enstatite 
occurs  in  a  few  scattered  grains.  They  are  fresh,  brownish-yellow,  finely  striated,  and 
crossed  by  cleavage-planes.  The  chromite  appears  in  little,  irregular,  rounded  grains. 

This  peridotite  is  associated  with  and  lying  in  schists,  and  is  called  by  Brogger  an 
olivine-sdiist.  \ 

Robcrgvik,  SkrenaJcJccn,  Norway. 

This  rock  was  described  by  H.  von  Mold  as  composed  principally  of  olivine  grains, 
containing  octahedrons  of  picotite  and  deep  hair-brown,  transparent,  chromite  crystals. 
Magnetite  was  present,  and  some  of  the  olivine  grains  showed  a  change  to  fibrous  chry- 
sotile.  Lamellae  of  fibrous  enstatite  were  seen.  § 

Bonhommc,   Bhdtenlerg ,   Vosycs,  France. 

A  blackish-green  rock,  with  a  rough,  splintery  fracture,  showing  a  brilliant  shimmer 
from  numberless  minute  points,  and  traversed  in  part  by  many  blackish  veins.  In  thin 
splinters  it  is  clear-green  and  translucent.  In  the  section  the  olivine  grains  are  seen  to 

*  Zcit.  Dcut.  geol.  Gcsell.,  186 1-,  xvi.  341-344;  Reise  dcr  Novara,  Geologic  von  Neu-Seeland,  pp.  217- 

220. 

f  Report  Cliiillrnircr  Expedition,  Narrative  ii.  Appendix  B.  pp.  22,  23. 
t  NCIICS  Jalir.  Min.,  1-^SO,  ii.  187-192. 
§  N}t  Mag.,  1877,  xxiii.  111. 

16 


122  PEEIDOTITE. 

be  clear  and  fresh,  but  in  some  points  a  change  to  serpentine  has  taken  place.     Picotite 
and  a  reddish  garnet  (?)  were  observed. 

The  other  accessories  were  a  few  plates  of  amphibole  minerals  and  iron  ores.* 

KarMaitcn,  Austria. 

Tschermak  describes  a  grayish-green,  fine-grained  rock  from  this  locality,  as  com- 
posed of  olivine,  united  with  serpentine,  grass-green  srnaragdite,  and  little,  black,  pitch- 
like,  or  semimetallic  grains  of  picotite. f 

Tron,   Oesterthal,  Norway. 

This  is  similar  to  the  serpentine  from  the  Andestad  See  to  be  later  described.  The 
olivine  grains  are  changed,  along  their  boundaries  and  fissures,  into  a  chrysotile.  This  is 
in  part  of  a  platy-granular  structure,  and  part  composed  of  parallel  fibres.  In  some  por- 
tions grains  of  olivine  with  unaltered  centres  are  to  be  seen.  Considerable  magnetite 
was  observed. 

Enstatite  is  comparatively  rare,  and  when  present  contains  some  picotite  grains  and 
crystals,  a  few  of  which  were  seen  in  the  olivine.J 

A  section  of  this  rock  obtained  from  R  Fuess  is  entirely  altered  to  serpentine.  The 
gray,  serpentine  groundmass  is  traversed  by  bands  of  ferruginous  and  gray  material, 
resembling  closely  those  represented  in  figures  1,  2,  and  4  of  Plate  V.  Dark-brown,  trans- 
lucent picotites  were  observed  scattered  through  the  serpentine,  their  borders  jagged  and 
opaque,  probably  as  a  result  of  alteration.  The  serpentine  is  filled  with  minute  black 
grains  of  some  iron  ore. 

ffeiersdorf,  Saxony. 

According  to  Dathe,  the  Heiersdorf  rock  is  medium  grained,  containing  pale-red  gar- 
nets, and  showing  under  a  lens  quartz  and  feldspar,  with  light-greenish  and  brownish 
olivine,  as  well  as  black,  lustrous  crystals.  The  principal  portion  of  the  section  is  oliviue. 
This  is  seldom  fresh,  but  generally  cloudy  or  altered  to  serpentine,  forming  the  usual  net- 
work, and  containing  some  dust-like  ore.  The  olivine  contains  some  picotite  or  chromite 
grains. 

Plates  of  magnesian  mica  occur  in  the  neighborhood  of  the  garnet  and  ore  particles. 
The  garnets  are  of  the  size  of  a  pin's  head,  and  are  somewhat  altered.  The  majority  are 
entirely  changed  from  the  singly-refracting  garnet  substance  to  a  doubly-refracting,  radi- 
ately-fibrous  material.  This  has  a  pale-blue  aggregate  polarization  color,  but  in  common 
light  is  greenish  and  feebly  dichroic.  The  minority  of  the  garnets  have  a  small  alteration 
zone  surrounding  them,  of  colorless  fibres,  probably  asbestus,  arranged  perpendicular  to 
the  garnet  boundary.  Light-brownish  zircon  grains  also  occur.  § 

Ronda  Mountains,  Spain. 

The  serpentine  of  the  Fionda  Mountains,  covering  an  area  of  nearly  600  square  miles 
has  been   described  as  eruptive  by  Joseph  Macpherson.  ||     With  the  serpentine   were 

*  Bruno  Weigaud.  Mm.  Mirth.,  1875,  pp.  186-192. 

f  Sitz.  Wien.  Akad.,  1867,  Ivi.  275-279. 

{  Nyt  Mag.,  1877,  xxiii.  120,  121. 

§  Neues  Jahr.  Min.,  1876,  pp.  227-229. 

||  On  the  Origin  of  the  serpentine  of  the  Ronda  Mountains,  J.  Macpherson,  Madrid,  1876,  20  pp.  2  plates. 


THE   TERRESTRIAL   PERIDOTITES.  —  DUNITE.  123 

found  imbedded  large  masses  of  peridotite.  The  peridotite  is  irregularly  disseminated 
through  the  serpentine,  showing  an  intimate  connection  of  the  two.  The  peridotite  is 
found  to  be  composed  of  olivine  grains,  traversed  by  numerous  fissures,  and  containing 
irregular  fragments  and  octahedrons  of  picotite.  The  rock  itself  usually  varied  from  a 
greenish-gray  to  various  shades  of  green. 

The  serpentine  is  generally  of  a  dark-green  color,  traversed  frequently  by  veins  of 
chrysotile,  and  not  uncommonly  charged  with  crystals  of  diallage.  It  is  said  that  in  some 
places  the  serpentine  "  is  traversed  by  great  parallel  planes  of  fracture,  which  at  first  sight 
might  be  mistaken  for  stratification." 

The  alteration  of  the  olivine  takes  place  along  the  fissures,  the  iron  separating  in  the 
serpentine  as  magnetite  and  chromite.  This  serpentinization  gradually  extends  until 
only  small  grains  of  olivine  are  left,  and  then  on  until  the  entire  rock  is  altered  to  serpen- 
tine. A  perfect  and  gradual  transition  was  traced  from  the  beginning  of  the  process  to 
the  complete  transformation.  The  alterations  are  shown  very  well  in  the  figures  accom- 
panying Macphersou's  paper. 

Serrama  de  Honda,  Spain. 

This  rock,  according  to  Macpherson,  is  of  a  clear,  greenish-gray  color,  with  a  lustre 
between  a  greasy  and  vitreous.  The  section  is  composed  of  a  crystalline-granular  aggre- 
gate of  olivine  fragments,  containing  numerous  picotite  grains.  The  olivine  shows  brilliant 
polarization  colors,  and  sometimes  a  striation  parallel  to  the  plane  of  extinction,  while  it 
is  traversed  by  irregular  fissures.* 

St.  Paul's  Hocks. 

These  rocks  were  described  by  Darwin  as  unlike  any  rock  he  had  met.  He  states : 
"  The  simplest,  and  one  of  the  most  abundant  kinds,  is  a  very  compact,  heavy,  greenish- 
black  rock,  having  an  angular,  irregular  fracture.  .  .  .  This  variety  passes  into  others  of 
paler-green  tints,  less  hard,  but  with  a  more  crystalline  fracture.  .  .  .  Several  other  varie- 
ties are  chiefly  characterized  by  containing  innumerable  threads  of  dark-green  serpentine, 
and  by  having  calcareous  matter  in  their  interstices.  These  rocks  have  an  obscure,  con- 
cretionary structure,  and  are  full  of  variously  colored  angular  pseudo-fragments.  .  .  . 
There  are  other  vesicular,  calcareo-ferruginous,  soft  stones.  There  is  no  distinct  strati- 
fication, but  parts  are  imperfectly  laminated,  and  the  whole  abounds  with  innumerable 
veins,  and  vein-like  masses,  both  small  and  large."  Darwin  states  that  the  rock  is  not 
of  volcanic  origin — not  necessarily  meaning  by  this  anything  more  than  that  it  was 
not  a  modern  eruptive  formation  like  that  of  the  other  islands  visited.f 

These  rocks  being  the  haunts  of  birds,  a  phospatic  incrustation  had  been  formed  on 
part  of  the  surface,  and  Professor  Wy  ville  Thomson  states  "  that  they  look  more  like  the 
serpentinous  rocks  of  Cornwall  or  Ayrshire,  but  from  these  even  they  differ  greatly  in 
character.  .  .  .  Mr.  Buchanan  is  inclined  to  regard  all  the  rocks  as  referable  to  the  ser- 
pentine group.  So  peculiar,  however,  is  the  appearance  which  it  presents,  and  so  com- 
pli'tdy  and  uniformly  does  the  phosphatic  crust  pass  into  the  substance  of  the  stone  that 
I  felt  it  difficult  to  dismiss  the  idea  that  the  whole  of  the  crust  of  rock  now  above  water 
might  be  nothing  more  than  the  result  of  the  accumulation,  through  untold  ages,  of  the 

*  Anal.  Soc.  Esp.,  Hist  N.it.,  1879,  viii.  251,  252. 
t  Volcanic  Iblands,  1851,  pp.  31-33,  125. 


124  PERIDOTITE. 

insoluble  matter  of  the  ejecta  of  sea-fowl,  altered  by  exposure  to  the  air  and  sun,  and  to 
the  action  of  salt  and  fresh  water."  * 

According  to  Rev.  A.  Eenard,  the  rock  is  composed  essentially  of  very  small  olivine 
grains  similar  to  those  of  the  New  Zealand  dunite.  Fluid  cavities  were  also  observed. 
Chromite  (picotite)  is  abundant  in  irregular,  generally  lenticular  grains,  of  a  brownish- 
yellow  color.  Eeuard  further  described  a  pale  green  mineral  of  irregular  outline,  and  a 
cleavage  forming  an  angle  of  124°,  which  he  assigned  to  an  amphibole  mineral.  Knsta- 
tite  in.  colorless  or  clear  greenish-yellow  sections  was  observed,  possessing  an  evident 
lamellar  structure.  A  structure  seen  in  the  sections  by  Eenard  was  regarded  by  him 
as  a  fluidal  structure.! 

In  a  later  publication,  M.  Eenard  seems  to  have  abandoned  his  idea  of  the  eruptive 
origin  of  these  rocks,  and  inclines  to  the  view  that  they  are  formed  from  crystalline 
schists,  the  supposed  fluidal  structure  being  really  schistose  structure  instead.  He 
regards  this  peridotite  as  remarkably  fresh  and  unaltered.  Color,  "  blackish-gray,  bordering 
green,  which  when  deep  looks  perfectly  black."  Its  component  minerals,  as  determined 
by  M.  Eenard,  are  olivine,  chromite,  actinolite,  enstatite,  and  a  pyroxenic  mineral  For  a 
fuller  description  the  reader  is  referred  to  the  original  papers.  J 

M.  Eenard  thinks  that  the  association  of  olivine  rocks  with  schists  proves  their  similar 
origin,  and  therefore  much  peridotite  is  sedimentary  ;  overlooking  the  fact  that  a  region  of 
eruptive  rocks  is  one  in  which  the  sedimentary  rocks  are  most  likely  to  become  schistose. 
Furthermore,  many  eruptive  rocks  are  schistose,  through  secondary  changes  in  them  after 
eruption.  Again,  many  eruptive  rocks  have  associated  with  them  ashes  and  other  frag- 
mental  material  of  eruptive  character,  as  well  as  sedimentary  deposits,  all  of  which  brings 
into  intimate  relations  metamorphosed  eruptive  rocks  and  schists.  This  is  a  case  to 
which  the  principles  earlier  given  in  this  volume  apply.  It  is  especially  difficult  to  see 
how  denudation  could  take  place  to  the  great  depth  in  the  ocean  required  when,  as 
M.  Eenard  admits,  there  is  no  evidence  of  depression. 

Two  specimens  of  this  rock  were  kindly  sent  me  by  Mr.  John  Murray,  of  the  Chal- 
lenger Expedition.  One  shows  on  the  fracture  a  dark  grayish-green  color,  and  as  M. 
Eenard  remarks,  closely  resembles  a  quartzite.  Weathers  to  a  yellowish  and  brownish- 
gray.  The  section  is  seen  to  be  composed  of  olivine,  enstatite,  diallage,  picotite,  chromite 
or  magnetite,  pyrite,  actinolite,  and  serpentine. 

M.  Eeuard  remarks  that  the  minerals  have  their  longer  axes  placed  parallel  with  the 
supposed  schistose  or  fluidal  structure.  In  this  section  the  larger  grains  stand  in  every 
direction,  some  of  the  olivine  grains  having  their  longer  axes  exactly  at  right  angles  to 
one  another.  No  structure  has  been  observed  by  me  that  I  should  regard  as  schistose. 
A  slight  schistose  appearance  has  been  produced  in  my  judgment  by  the  secondary  altera- 
tion of  the  rock.  Fortunately,  one  of  the  specimens  sent  me  is  of  the  rock  said  by  M. 
Eenard  to  be  entirely  fresh  and  unaltered.  He  also  states  that  the  structure  of  this  rock 
is  peculiar,  and  unlike  that  of  other  olivine  rocks.  In  one  section  a  portion  of  the  rock  is 
only  slightly  altered,  and  this  portion  shows  the  common  structure  of  peridotites.  The 
main  mass  of  the  rock,  described  by  M.  Eenard  as  the  groundmass,  is  in  my  opinion 
greatly  altered,  and  contains  only  the  remnants  of  the  original  minerals,  surrounded  by 
their  alteration  products.  M.  Eenard  regards  this  groundmass  as  composed  entirely  of 

*  Voyage  of  the  Challenger,  ii.  100-108.  t  Neues  Jahr.  Min.,  1879,  pp.  389-394. 

J  Report  of  tlie  Scientific  Results  of  the  exploring  Voyage  of  II.  M.  S.  Challenger,  1873-76.  Narrative, 
vol.  ii.  Appendix  B.,  29  pp.,  1  plate ;  Description  Lithologique  dcs  llecifs  des  St.  Paul,  extrait  des  Annales 
de  la  Societe  beige  Microscopic,  1882,  53  pp. 


& 


TJIK   TKRUKSTHIAL    PKPJDOTITES.  — SAXON1TE.  125 

olivine  grains,  but  of  this  I  have  grave  doubts.  The  characters  as  seen  microscopically 
do  not  appear  to  me  to  be  those  of  ordinary  olivine,  but  rather  those  of  one  or  more  min- 
erals of  secondary  origin.  That  this  groundmass  is  of  secondary  origin,  for  the  most  part, 
is  shown  by  its  occurrence  along  the  fissures  in  the  unaltered  olivines,  by  its  relations  to 
the  minerals  which  it  surrounds,  which  are  the  same  as  those  existing  in  other  rocks 
between  thu  original  minerals  and  their  secondary  products,  and  by  the  secondary  schis- 
t"-'1  structure.  In  such  cases  as  these  much  depends  upon  the  experience  and  especial 
kind  of  work  that  the  observer  has  done,  and  unfortunately  such  evidence  cannot  be 
placed  in  words  so  as  to  enable  others  to  judge  of  its  correctness. 

It  is  contrary  to  the  laws  of  physics  and  chemistry  that  a  mineral  in  altering  should 
produce  itself  again  —  there  is  rather  a  passage  from  an  unstable  compound  in  the  condi- 
tions in  which  it  then  is,  to  one  more  stable  in  the  same  conditions.  If  I  am  right  regard- 
ing this  alteration  of  the  olivine  the  resulting  mineral  or  minerals  must  belong  either  to 
another  variety  of  olivine  or  to  a  distinct  species. 

The  actinolite,  chromite,  picotite,  magnetite,  pyrite,  and  serpentine,  I  regard  in  this 
case  as  secondary  products  in  the  rock,  and  not  original  ones. 

As  said  before,  in  places  the  section  shcjws  the  olivine  unaltered,  and  having  the  same 
relation  between  the  grains  that  exists  in  other  rocks  when  the  granular  structure  is  due 
to  crystallization  from  an  igneous  magma,  and  not  from  detrital  action.  M.  Eenard  has 
pointed  out  that  the  actinolite  is  more  abundant  in  the  fine  groundmass  than  elsewhere  in 
the  sections,  which  is  in  accord  with  my  view  of  their  origin.  One  section  shows  at  one 
end  that  it  is  composed  chiefly  of  a  confused  mass  of  pale-greenish  mouoclinic  crystals, 
showing  cross  fracture,  and  which  are  here  referred  to  actinolite. 

An  examination  of  sections  from  the  more  highly  altered  rock  shows  that  on  further 
alteration  the  fine  grouudmass  becomes  changed  from  a  clear  to  a  dirty-yellowish  one,  but 
slightly  polarizing.  The  hand  specimens  sent  me  bear  evidence  that  they  are  surface  and 
weathered  specimens  —  to  which  probably  much  of  the  difficulty  in  their  study  is  due; 
for,  judging  from  M.  Eenard's  descriptions,  he  had  similar  specimens  to  mine.  In  this  I 
would  by  no  means  judge  of  what  M.  Ilenard  saw,  but  only  of  the  sections  that  I  have 
myself  studied. 

It  is  to  be  hoped  that  should  these  rocks  ever  be  visited  again  great  pains  would  be 
taken  to  procure  specimens  as  deep  in  the  solid  rock  as  it  is  possible  to  obtain  them.* 

VARIETY.  —  Saxonite. 

Russdorf,  Saxony. 

Dathe  described  a  peridotite  from  Ilussdorf,  Saxony,  as  fine-grained,  and  of  a  light- 
'_:iveii  color.  Olivine  formed  the  essential  portion  of  the  rock-mass.  This  mineral  was 
slightly  altered  on  its  edges  to  a  granular  substance  of  a  light-yellowish  to  brownish  color ; 
aK»,  along  the  fissures  the  olivine  grains  are  changed  to  a  light-yellowish,  almost  homoge- 
neous mass.  Inclosed  in  the  olivine  are  black  octahedral  crystals  of  picotite  or  chromite. 
The  enstatite  shows  in  colorless,  finely-striated  sections.  Olivine  in  small  grains  and 
small  black  needles  was  observed  inclosed  in  the  enstatite.f 

Northern  Norway. 

Holland  describes  some  of  the  peridotites  from  Northern  Xorway  as  composed  of  fresh 
olivine,  containing  picotite,  together  with  cnstatite  and  grains  of  iron  ore.  Serpentine 

»  Science,  1883,  i.  590-59:2.  t  Ncues  JaLr.  Miu.,  1876,  pp.  233-235. 


126 


PERIDOTITE. 


from  this  region  was  found  composed  of  serpentine,  with  olivine  fragments,  and  magne- 
tite.    Another  serpentine  rock  contained  only  serpentine,  diallage,  and  magnetite.* 

T/iorsvig,  Norway. 

This  rock  is  stated  by  Mohl  to  contain  60  per  cent  of  olivine,  30  per  cent  of  eustatite, 
and  10  per  cent  of  anorthite  and  magnetite.  The  olivine  and  anorthite  were  in  grains, 
and  the  enstatite  in  table-like  forms,  without  crystalline  contour.f 

BirJccdal,  Norway. 

From  Birkedal,  Norway,  according  to  Mohl,  was  obtained  a  peridotite  composed  of 
olivine  and  enstatite,  with  some  magnetite,  chromite,  mica,  and  anorthite  —  the  latter 
mineral  composing  about  10  per  cent  of  the  rock-mass.J 

Hovden,  Horningdal,  Norway. 

This  peridotite,  according  to  Mohl,  is  composed  of  olivine  grains  and  enstatite  plates, 
with  magnetite  and  brown  mica.  The  enstatite  is  in  part  of  a  light  yellowish-gray,  and 
in  part  a  very  strong  nacarat  color.  It  is  cut  through  by  parallel  fissures,  is  fibrous,  and 
contains  many  loose  aggregates  of  brown  needles  and  laminae.  § 

Rodfjeld,  Norway. 

Dr.  H.  von  Mohl  described  a  rock  from  Rodfjeld,  Murusjo,  Norway,  as  made  up  of 
olivine  grains,  enstatite,  and  a  little  ledge-formed  feldspar.  The  olivine  in  places  is 
described  as  suffering  a  total  change  to  chrysotile.  || 

Andestad  See,  Aure,  Nonvay. 

This  stone,  according  to  Mohl,  is  composed  of  75  per  cent  of  olivine  in  angular  grains, 
20  per  cent  of  enstatite  and  tabular-formed  aggregates,  and  5  per  cent  of  chromite  in 
granular  aggregations. 

Only  a  small  portion  of  the  olivine  remains  clear  and  fresh.  Around  the  contour  of 
the  freshest  grains  wind  strings  of  a  dirty  greenish-yellow  chrysotile.  The  grains  them- 
selves are  sometimes  of  a  dirty  grayish-yellow  color  or  cloudy,  and  show  aggregate  polar- 
ization. Here  and  there  a  grain  is  entirely  changed  to  a  nearly  opaque  liver-brown 
serpentine. 

The  enstatite  is  nearly  colorless,  beautifully  cleaved,  and  here  and  there  is  finely 
fibrous  —  the  fibres  being  parallel.  ^[ 

In  part,  this  rock  is  so  far  changed  to  serpentine,  that  only  here  and  there  do  the 
olivine  grains  show  any  clear  central  portions  remaining.  The  enstatite  remains  in  part 
as  fresh  as  in  the  preceding,  except  in  its  cross  fractures,  which  are  filled  with  chrysotile. 
In  part,  the  enstatite  is  completely  serpentinized,  but  recognizable  on  account  of  its 
platy  pores  and  its  parallel  fibrous  structure.  The  chromite  remains  unchanged.  *' 

A  section  of  the  Andestad-  See  peridotite,  purchased  from  Eichard  Fuess,  of  Berlin, 


*  Nencs  Jalir.  Miu.,  1879,  p.  422. 
}  Nyt  Mag.,  1877,  xxiii.  116. 
||  Nyt  Mag.,  1877,  xxiii.  113,  114. 
**  Nyt  Mag.,  1877,  xxiii.  119,  120. 


f  Nyt  Mag.,  1877,  xxiii.  115. 
§  Nyt  Mag.,  1877,  xxiii.  110. 
U  Nyt  Mag,  1877,  xxiiL  118, 119. 


THE  TERRESTRIAL   PERIDOTITES.  —  SAXONITE.  127 

• 

lias  the  following  characters :  A  yellowish-green  groundinass,  holding  several  crystals  of 
enstatite.  Under  the  microscope  the  section  is  seen  to  be  formed  by  a  serpentine  plexus 
holding  dlivine,  enstatite,  and  chromite.  The  olivine  remains  only  in  small  grains,  sur- 
rounded by  the  serpentine,  to  which  the  remainder  of  the  olivine  mass  has  been  changed. 
The  olivine  is  generally  very  pure  and  clear,  but  its  fissures  are  traversed  by  the  serpen- 
tine ;  grains,  even  some  little  distance  apart,  showing  in  polarized  light  that  they  are  por- 
tions of  the  same  crystal. 

Figure  4,  Plate  IV.,  shows  the  structure  of  this  section.  The  greenish  portion  repre- 
sents the  serpentine,  the  grayish-white  portion  at  the  upper  part  of  the  section  is  the 
partly  altered  enstatite,  the  white  grains  inclosed  in  the  greenish  serpentine  mass  are  oli- 
viue,  and  the  dark  grains  are  chromite. 

Lctnycnbcrff,  Saxony. 

A  dull,  black,  serpentine  mass,  holding  numerous  brownish-black  bronzite  (enstatite) 
crystals.  In  the  thin  section  the  bronzite  crystals  show  an  extraordinarily  fine,  wavy, 
fibrous  structure,  parallel  with  the  extinction  plane.  It  contains  arranged  along  the 
planes  of  the  fibres  little  opaque  needles,  and  pellicles  of  hydrous  oxide  of  iron,  and  is  par- 
tially altered  to  a  feebly  doubly-refracting  substance  —  serpentine.  Sometimes  the  crys- 
tals are  cloudy  and  altered  —  bastite.  The  olivine  has  been  altered  to  serpentine,  having 
the  usual  maschen  texture.  Magnetite  (?),  and  little  crystals  of  chromite  (?)  were  also 
observed.* 

Calknberg,  Saxony, 

This  rock  has  a  blackish-green  to  brown  color,  and  contains  little  bronzite  crystals. 
In  the  section  the  olivine  is  seen  to  have  been  replaced  by  serpentine,  with  the  usual 
network  structure.  The  bronzite  is  also  more  or  less  altered,  and  chromite,  hematite,  and 
other  iron  ores  were  observed.! 

The  Ziegclei,  between  Russdorf  and  Meusdorf,  Saxony. 

A  leek-green  serpentine,  containing  bastite  (enstatite)  crystals.  The  section  shows 
the  mesh  structure  of  serpentine  divided  from  olivine,  and  fibrous-bastite  (enstatite)  with 
chromite  and  other  iron  ores.  $ 

Fain  LuJca  and  Fatu  Termanu,  Timor. 

This  rock,  according  to  Wichmann.  is  of  an  oil-green  to  blackish-green  color,  and 
holds  brouzite  and  chromite.  Under  the  microscope  the  serpentine  shows  the  mesh  struc- 
ture, indicating  its  alteration  from  olivine.  The  meshes  are  light-green  to  colorless,  and 
the  interstitial  spaces  of  a  brownish-green  color.  The  bronzite  (enstatite)  in  the  section  is 
colorless,  and  free  from  all  inclusions,  except  secondary  products.  § 

Rofna,  Alps. 

A  compact,  dark,  purplish-green  rock,  containing  folia  of  enstatite,  having  a  jointed, 
crushed  structure,  with  the  sides  coated  with  greenish  serpentine,  and  presenting  a  schis- 

«  Datho,  Ncucs  Jahr.  Miu.,  1876,  pp.  338,  339.  f  Dathe,  Neues  Jabr.  Min.,  1876,  pp.  339-341. 

J  Dnthr.  Nnirs  Jahr.  Min.,  1876,  p.  339. 

§  Jaarboek  van  bet  Mijnwezen  in  Nederlandsch  Oost-Indie,  1882,  pp.  211-213. 


128  PEKIDOTITE. 

tose  aspect.  Tlie  section  shows  a  reticulated  network  of  opacite,  with  interspaces  having 
a  fibrous  border  and  a  granular  centre  of  serpentine.  The  section  further  contains  some 
enstatite  altered  to  serpentine,  magnetite,  and  a  little  picotite,  or  chromite,  and  hematite. 
This  is  regarded  as  an  altered  olivine-enstatite  rock.  Further  examination  of  these  Alpine 
serpentines  showed  that  they  were  either  derived  from  rocks  of  this  character,  or  else 
from  olivine-augite-eustatite  rocks.* 


VARIETY.  —  Lherzolite. 

Lake  Lhcrz,  France. 

The  famous  Iherzolite  occurring  about  Lake  Lherz,  and  at  various  localities  between 
that  lake  and  Vicdessos  and  Sem,  in  the  department  of  Ariege,  in  the  Pyreneean  region  of 
Southern  France,  has  been  described  by  Professor  T.  G.  Bouney  as  a  crystalline  aggregate 
of  olivine,  enstatite,  and  diallage  (diopside),  with  some  picotite ;  the  texture  varying  from 
a  finely  to  a  coarsely  granular.  Color  on  the  fresh  fracture,  a  dark  greenish-gray  or  olive- 
green.  The  rock  on  close  inspection  shows  specks  of  emerald-green  diallage,  waxy  look- 
ing, dull-green  serpentine,  resinous,  pale-brown  enstatite,  and  minute  grains  of  picotite, 
inclosed  in  the  predominant  dull-colored,  or  glassy,  olivine  mass. 

The  sections  are  grayish  to  water-clear  aggregates  of  olivine,  enstatite,  and  diallage, 
holding  picotite.  The  section  is  traversed  by  a  network  of  fissures,  and  is  thus  coarse  or 
fine-granular  in  different  portions.  The  oliviue  is  in  rounded,  water-clear,  more  or  less 
irregular  grains,  and  is  the  predominant  mineral,  forming,  according  to  Zirkel  and  Bonney 
two-thirds  of  the  whole  mass  of  the  rock.  The  enstatite  is  clear,  colorless,  and  sometimes 
shows  a  slight,  silky  texture.  The  diallage,  like  the  enstatite,  is  in  irregular  fragments, 
sometimes  clear  and  transparent,  and  at  others  shows  a  faint  tinge  of  green.  Both  it  and 
the  enstatite  are  often  feebly  dichroic,  varying  from  colorless  to  various  pale  shades  of 
green.  Sometimes  the  diallage  varies  simply  in  the  depth  of  the  green  tint.  These  min- 
erals are  not  to  be  certainly  distinguished  one  from  the  other,  except  by  their  optical 
characters. 

The  picotite  occurs  in  coffee-brown,  irregular  masses  and  grains,  the  latter  often 
grouped  together  in  little  masses,  scattered  along  from  the  ends  of  some  larger  mass. 
The  color  is  sometimes  a  yellowish-green,  and  Professor  Bonney  describes  some  as  being 
of  a  deep  olive-green.  I  should  regard  the  picotite  as  being  the  first  formed  mineral, 
instead  of  the  last,  as  he  regards  it.  In  some  portions  of  the  sections  serpentine  has  been 
formed  along  the  fissures,  showing  fibrous  polarization,  the  fibres  sometimes  lying  parallel, 
sometimes  perpendicular  to  the  walls.  Near  these  serpentine  veins  the  olivine  is  dark- 
ened along  its  fissures,  apparently  from  the  separation  of  magnetite  or  chromite  in  a  fine 
powder.  In  some  cases  these  black  grains  are  united  into  irregular,  branching,  spiney 
masses.  Masses  of  these  black  aggregations  are  seen  arranged  in  the  centre  of  the  vein- 
lets  of  the  serpentine,  like  islets  in  a  stream.  Professor  Bonney,  in  his  sections,  was  able 
to  trace  the  alteration  of  the  oliviue  to  serpentine,  one  of  his  sections  showing  a  network 
of  serpentine  veins  surrounding  and  penetrating  the  other  minerals.  In  the  sections 
before  me,  the  olivine  is  in  some  cases  changed  to  a  pale-greenish  serpentine,  holding 
minute  aggregations  of  the  ferruginous  grains.  These  serpentine  masses  are  generally  iso- 
tropic,  although  showing  in  a  few  points  the  fibrous  aggregate  polarization  of  serpentine. 

*  Bouncy,  Geol.  Mag.,  18SO  (2),  vii.  538-542. 


THE   TERRESTRIAL   PERIDOTITES.  —  LHERZOLITE.  129 

This  isotropic  character  of  the  early  stages  of  the  alteration-products  of  minerals,  has 
been  frequently  observed  by  the  present  writer  in  the  case  of  many  other  minerals. 

The  sections  herein  described  are  of  two  slides,  from  Voigt  and  Hochgesang,  purport- 
ing to  come  from  Vicdessos  (European  Collection,  Nos.  71  and  165).  Some  additions 
have  also  been  made  from  the  excellent  description  of  Professor  Bonney,  to  which  the 
student  is  referred.* 

This  Iherzolite  was  regarded  by  Bonney  as  undoubtedly  eruptive,  on  account  of  its 
observed  relations  to  the  adjacent  rock.f 

Scrrania  dc  Honda,  Spain. 

This  rock,  according  to  Macphersou,  has  a  greenish  groundmass  of  olivine,  holding 
emerald-green  diopside.  Under  the  microscope  it  is  seen  to  be  composed  of  olivine, 
enstatite,  and  diallage  (diopside). 

The  diallage  is  of  a  clear  green  color,  dichroic,  and  has  a  fibrous  structure.  The 
olivine  is  clear  and  fissured,  but  shows  in  places  a  partial  change  to  serpentine.  The 
enstatite  resembles  the  diallage  in  its  general  characters,  but  Las  a  yellowish  color. 
Picotite  is  common.} 

Italy. 

Numerous  peridotites  —  Iherzolites  and  serpentines  —  have  been  described  from  Italy 
by  tin;  Italian  lithologists,  particularly  by  Professors  Alfonso  Cossa  and  Torquato  Tara- 
melli.  These  appear  to  be  composed  principally  of  olivine,  enstatite,  diallage,  and  picotite, 
and  their  secondary  products.  Most  of  the  serpentines  seemed  to  have  been  formed  by 
the  alteration  of  the  Iherzolite  variety  of  peridotite.  Cossa's  work  contains  many  valu- 
able chemical  analyses  of  the  olivine  rocks  which  have  been  tabulated,  and  for  the  general 
descriptions  and  plates  the  student  is  referred  to  Cossa's  Eicerclie  Chimiche  e  Microsco- 
piche  su  Eoccie  e  Mineral!  d' Italia,  Turin,  1881 ;  and  to  the  publications  of  the  "Accade- 
inia  dei  Lincei"  of  Rome. 

Ultcnthal,  Tyrol. 

A  coarse,  granular,  greenish-white  rock,  according  to  Sandberger,  holding  bronzite, 
chromdiopside,  and  picotite,  in  grains  and  rounded  octahedrons.  A  fine-grained  variety 
shows  a  schistose  structure,  and  holds  rose-red  and  deep  blood-red  pyrope.  This  rock  is 
altered  in  part  to  serpeutine.§ 

Rilcjc  between  Indian  and  Dear  Valleys,  Colusa  Co.,  Col. 

3001.  A  yellowish  and  grayish-brown  groundmass,  containing  porphyritically 
enclosed  somewhat  bronze-like  crystals  of  eustatite  and  diallage.  Under  the  lens  the 
groundmass  shows  a  greenish  network,  holding  a  yellowish  or  gray  substance  between  the 
nii'shes.  Section  :  a  greenish-white  crystalline  mixture  of  olivine,  enstatite,  and  diallage. 

*  Geol.  Mag.,  1877  (2),  iv_59-f>4. 

f  See  also  Charpentier,  Journal  des  Minos,  1S12,  xxxii.  321-340  ;  Essai  sur  la  Constitution  G^ogno- 
stiq.ie  iles  IWnees,  1^:1,  pp.  il.'i-JUl..  Ann.  Pliysik,  181 1,  Ivii.  201-208;  Delam6thcric,  Tlicorie  cle  la 
Torre,  17!»7  (3d  nl.),  ii.  2sl,  2S2;  Le?ous  dc  Mineralogie,  1S12,  ii.  20(5,  207;  Picot  dc  Lapeyrouse,  Mem. 
\<  M|.  Toulouse,  iii.  410;  Lelicvre,  Journal  dc  Physique,  1787,  xxx.  397,  398;  Vogel,  Journal  des  Mines. 
1813,  xxxiv.  71-74;  Zirkel,  Zoit.  Dout.  «m\.  Gesell.,  ISC,;,  xix.  138-148  ;  Damour,  Bull.  Soc.  Geol.  France, 
ISO:!  (-2),  xix.  413-416;  J.  Kiilin,  Zeit.  De.it.  -ml.  Gesell.,  1SS1,  xxxiii.  398. 

J  Anal.  Soc.  E*|i.  lli-t.  X:it.,  1^7'.l.  viii.  253-258. 

§    Xeues  Jalir.  Mill.,   Mid,  pp.  449,  450. 


130  PERIDOTITE. 

The  whole  is  traversed  by  a  reticulated  series  of  fissures,  which  in  each  mineral  partakes 
of  its  usual  mode  of  fracturing. 

The  olivine  is  the  predominating  mineral.  It  forms  rounded  irregular  grains  traversed 
by  numerous  fissures.  Larger  fissures  surround  the  main  olivine  masses,  these  veins  being 
marked  by  a  yellowish-brown  central  line  of  earthy  ferruginous  and  serpentinous  mate- 
rial, on  each  side  of  which  extend  borders  of  pale-green  serpentine.  The  borders  are  of 
various  widths,  and  usually  ramify  in  little  veinlets  of  serpentine  through  the  fissures 
intersecting  the  olivine  individual.  In  places,  the  entire  olivine  is  altered  to  serpentine. 
The  serpentine  in  polarized  light  usually  shows  fibrous  polarization,  the  fibres  being 
arranged  perpendicular  to  the  sides  of  the  fissures.  The  yellowish-brown  earthy  mate- 
rial that  marks  the  medial  line  of  the  main  veins  has  entirely  replaced  the  olivine  in 
some  portions  of  the  section,  giving  rise  to  brownish  patches.  The  serpentine  is  filled, 
along  various  planes  and  especially  along  the  central  line  of  the  veins,  with  innu- 
merable minute  fluid  cavities,  so  minute  that  even  magnified  over  nine  hundred  diame- 
ters they  remain  as  fine  black  globulitic  specks,  totally  reflecting  the  transmitted  light. 
Occasionally  one  larger  than  the  rest  shows  the  narrow  outline  of  the  common  full  fluid 
cavity. 

The  enstatite  is  in  elongated  crystals  and  irregular  grains,  traversed  by  the  usual  fine, 
fibrous  cleavage.  The  surface  of  the  crystals  is  somewhat  smooth  and  silky,  and  the 
principal  cleavage  is  broken  occasionally  by  fractures  running  obliquely  across  the  crys- 
tals. The  larger  enstatites  frequently  show  a  greenish  fibrous  alteration  extending  along 
the  fissures  and  sometimes  reaching  the  main  body  of  the  crystal. 

The  diallage  is,  like  the  enstatite  in  most  of  the  sections,  clear  and  colorless.  It  can 
generally  be  distinguished  from  the  latter  mineral  by  the  roughness  and  irregularity  of 
its  cleavage,  owing  to  the  acute  angle  at  which  two  of  the  cleavages  meet  in  most  of  the 
grains.  Like  the  smaller  enstatites,  the  diallage  is  in  irregular  grains  and  masses,  and  both 
occasionally  contain  rounded  grains  of  olivine,  and  crystals  and  grains  of  picotite.  In  one  or 
two  cases  grains  were  observed  showing  the  cleavage  of  augite.  Some  of  the  diallage  plates 
have  an  earthy-white  or  cloudy  appearance,  marking  a  certain  amount  of  alteration. 
Sometimes  both  the  enstatite  and  diallage  are  traversed  by  serpentine  veins,  and  the 
smaller  grains  surrounded  by  that  mineral. 

Picotite  occurs  in  yellowish-brown  octahedrons,  as  well  as  in  irregular  masses,  opaque 
for  the  most  part,  but  translucent  and  of  a  yellowish-brown  color  in  places.  How  much 
of  this  might  properly  come  under  the  head  of  chromite  can  not  be  told.  In  the  yellow- 
ish-brown serpentine  veins  are  arranged  grains  showing  the  lustre  of  magnetite,  which 
mineral  is  also  seen  in  some  portions  of  the  before-mentioned  opaque  irregular  masses  of 
picotite  (?). 

The  microscopic  structure  of  the  rock  is  shown  in  figure  1,  Plate  V.,  which  indicates 
the  grayish,  fissured,  partly  altered  olivine  and  eustatite  grains,  the  dark  picotite  grains, 
and  the  brownish  veins  traversing  the  rock-mass. 

This  rock  was  described  by  the  collector,  Mr.  W.  A.  Goodyear,  as  metamorphic,  but 
with  the  stratification  generally  almost  obliterated.  Mr.  Goodyear  probably  took  a  some- 
what banded  arrangement  of  the  minerals,  as  observed  in  No.  3002,  and  a  tendency  to 
split  into  platy  masses,  for  stratification.  Since  both  of  these  are  common  in  eruptive  rocks, 
the  latter  showing  especially  on  alteration  and  weathering,  further  evidence  is  required 
upon  the  subject.  Microscopically  and  lithologically  they  belong  to  rocks  which  the  best 
evidence  pronounces  to  be  eruptive.  It  is  to  be  hoped  that  future  geologists,  in  visiting 
the  locality,  will  endeavor  to  settle  the  question  of  the  origin  of  these  most  interesting 


THE   TERRESTRIAL   PERIDOTITES.  —  LHERZOLITE. 

rocks  by  an  examination  of  their  relations  to  the  associated  rocks.  Of  the  occurrence 
Mr.  Goodyear  states:  "  The  great  mass  of  the  rock  throughout  the  whole  ridge  consists 
of,  apparently,  a  serpentinoid  matrix,  filled  with  foliated  crystals  of  a  hard,  green  mineral, 
which  I  suspect  to  be  pyroxene,  forming  a  rock  similar  to  that  of  which  large  quantities 
occur  near  Guenoc  and  Coyote  Valley.  But  there  are  also  immense  quantities  of  serpen- 
tine without  these  crystals."* 

The  associated  rocks,  according  to  Mr.  Goodyear,  were  some  hard  metamorphic  sand- 
stones, and  a  few  shales. 

No.  3002  is  from  the  same  locality. 

This  has  a  reddish-brown  groundmass,  holding  crystals  of  enstatite  and  diallage.  The 
same  reticulated  network  is  observed  in  the  groundmass  as  in  the  preceding,  but  the  in- 
closed portions  are  of  a  yellowish-  or  reddish-brown  color.  A  roughly  banded  appearance  is 
produced  by  a  somewhat  linear  arrangement  of  the  enclosed  crystals.  Both  this  and  the 
preceding  are  surface  specimens.  Some  of  the  crystals  in  No.  3002  show  the  well- 
marked  characters  of  bronzite.  Section  :  this  is  composed  of  a  reticulated  network  of 
serpentine  veins,  holding  rounded  and  irregular  grains  of  olivine,  enstatite,  and  diallage  ; 
while  larger  enstatite  crystals  are  porphyritically  enclosed.  This  rock  was  evidently  once 
a  crystalline-granular  mass  of  olivine,  enstatite,  and  diallage,  but  now  it  exhibits  a  stage 
of  alteration  somewhat  in  advance  of  that  shown  in  No.  3001.  The  same  reticulated 
network  of  serpentine,  with  the  same  reddish-brown  medial  line,  is  to  be  observed  as  in 
the  preceding ;  in  fact,  the  structure  of  the  two  rocks  is  identical.  The  serpentine  ex- 
tends from  the  medial  line  of  the  veins  inward  along  the  fissures,  until  only  portions 
of  the  original  minerals  are  left  surrounded  by  it.  In  many  cases  the  serpentine  has  re- 
placed the  entire  mass  of  the  rock,  but  still  retains  the  marks  of  the  fissures  along 
which  the  alteration  took  place.  The  serpentine  extending  out  from  the  reddish-brown 
portion  of  the  veins  is  of  a  pale  greenish-yellow  color,  and  shows  fibrous  and  aggregate 
polarization  —  the  fibres,  as  usual,  being  perpendicular  to  the  sides  of  the  vein.  While 
part  of  the  olivine  lying  inclosed  in  this  network  is  unchanged,  much  of  it  has  been 
altered  to  a  reddish-brown  serpentinous  mass  like  that  forming  the  centre  of  the  veins. 
In  many  cases  this  last  extends  only  partly  through  the  olivine  grain  leaving  a  central 
portion  of  unchanged  olivine,  but  in  others  the  alteration  is  complete.  This  reddish- 
brown  alteration  shows  a  tendency  to  extend  in  fibres  parallel  to  the  crystallographic  axis, 
or  along  the  latent  cleavage  planes.  The  general  characters  given  in  describing  the  minerals 
in  No.  3001  hold  good  here.  The  enstatite  is  more  highly  altered  to  the  greenish  fibrous 
product,  while  it  is  frequently  crossed  by  fissures  at  right  angles  to  the  principal  cleavage. 
The  serpentine  veins  in  this  and  in  the  diallage  are  more  abundant  and  pronounced  than 
in  No.  3001 ;  but  these  minerals  evidently  are  more  slowly  altered  than  the  olivine.  Of 
the  eustatite  and  diallage,  the  former  is  the  more  readily  changed.  Picotite  or  chroinite 
occur  as  before,  but  in  somewhat  larger  masses. 

Figure  2,  Plate  V.,  shows  the  general  microscopic  structure  of  this  rock,  the  dark  to 
black  portions  representing  the  iron-ore  grains ;  the  white  portions  are  the  unchanged  oli- 
vine, the  orange-brown  and  yellow  colors  mark  the  differently  altered  portions  of  the 
olivine  (serpentine),  while  the  dark-brown  bands  are  serpentine  veins  like  those  which 
are  shown  to  some  extent  in  figure  1  of  this  plate. 

Figure  3,  Plate  V.,  is  from  the  same  rock,  and  shows  the  structure  of  the  partly 
altered  enstatite.  The  main  portion  of  the  figure  is  that  mineral  with  its  cleavage  lines 

*  Unpublished  Report  made  to  Professor  J.  D.  Wliitncy. 


132  PEEIDOTITE. 

and  alteration-products  represented  by  the  gray  and  brown  lines  running  from  top  to 
bottom.  The  enstatite  crystal  is  crossed  from  right  to  left  by  a  yellowish  serpentine  vein 
connecting  two  portions  of  the  altered  olivine  mass  represented  by  the  mixed  brown, 
yellow,  and  white.  The  dark  grains  are  the  iron  ores,  or  picotite. 

Figure  1,  Plate  VII.,  represents  an  enstatite  crystal  from  the  same  rock,  in  a  more 
highly  altered  condition.  The  primary  cleavage  runs  from  right  to  left,  and  the  secondary 
from  top  to  bottom.  The  greenish  color  shows  the  earlier  stages  of  the  alteration,  and 
the  yellow  color  the  following  or  serpentine  stage,  although  part  of  the  serpentine  mate- 
rial may  have  been  brought  in  from  the  surrounding  olivine  mass  not  shown  in  the 
figure. 

Foot  of  divide  between  Round  Valley  and  Bullfrog  Creek,  Inyo  Co.,  Cul. 

3003.  A  compact  oil-green  groundmass,  holding  bluish-black  and  bronze-like  crys- 
tals of  enstatite.  The  rock  is  traversed  by  a  few  veins  of  pale-green  serpentine,  while 
a  chrysotile  vein  occurs  at  one  end. 

Section :  a  yellowish-green  groundmass,  holding  porphyritically  enclosed  some  dark 
enstatite  plates.  The  groundmass  shows  under  the  microscope  the  same  reticulated  net- 
work of  veins  as  that  seen  in  3001  and  3002,  the  veins  being  readily  distinguishable 
both  in  common  and  polarized  light.  While  the  structure  remains  in  general  the  same  as 
in  3001  and  3002  the  entire  groundmass  is  changed  to  serpentine :  that  is,  it  is  a  dis- 
tinct pseudomorphous  replacement  by  serpentine  of  all  the  essential  structural  character- 
istics of  the  preceding  rocks.  Even  black  opaque  masses  are  seen  having  all  the  structural 
features  of  the  picotite  of  Nos.  3001  and  3002. 

Much  magnetite  or  chromite  is  seen  scattered  throughout  the  grouudmass,  or  collected 
into  open  aggregations.  The  enstatite  in  some  cases  retains  its  usual  polarization  charac- 
ters, with  the  well-marked  cleavage.  In  others  it  has  been  so  highly  altered  that  only 
traces  of  the  cleavage  and  the  orthorhombic  extinction  in  polarized  light  remain  of  its 
usual  diagnostic  features.  All  the  enstatites  are  filled  with  grains  of  magnetite,  which  in 
some  crystals  are  arranged  along  the  cleavage  lines.  The  powder  of  the  enstatite  crystals  is 
magnetic,  and  it  is  to  the  magnetite  that  their  bluish-black  color  is  due.  The  magnetite 
is  regarded  as  a  product  formed  during  the  conversion  of  the  rock  into  serpentine.  The 
evidence  afforded  by  the  microscopic  structure  of  this  rock,  it  seems  to  me,  is  proof  posi- 
tive that  this  serpentine  was  formed  from  the  metamorphism  of  a  peridotite,  the  beginning 
of  which  change  is  to  be  seen  in  No.  3001,  and  still  further  advanced  in  No.  3002. 

The  general  structure  of  this  section  is  shown  in  figure  4,  Plate  VI.,  which  displays 
an  altered  enstatite  crystal  with  its  secondary  magnetite,  surrounded  by  the  serpentine 
replacing  the  oliviue. 

Mohsdorf,  /Saxony. 

This  rock,  according  to  Dr.  E.  Dathe,  is  compact,  blackish-green,  and  contains  crystals 
of  diallage  and  enstatite,  which  show  a  mother-of-pearl  to  silky  lustre,  and  a  light-yel- 
lowish color,  while  they  are  finely  striated.  The  principal  material  of  the  section  is 
olivine,  part  of  which  is  in  large  rounded  grains  with  few  fissures,  and  part  in  smaller 
grains,  traversed  by  cracks,  and  more  or  less  altered  to  a  greenish-fibrous  serpentine. 
The  olivine  contains  little  octahedral  crystals  of  chromite  or  picotite,  with  rounded  angles. 
The  enstatite  is  in  light-greenish,  elongated  sections,  sometimes  holding  olivine  grains,  and 
traversed  by  cleavage  lines  parallel  to  010.  Diallage  also  occurs,  recognized  by  its  opti- 


THE  TERRESTRIAL   PERIDOTITES.—  LHERZOLITE.  133 

cal  relations  and  cleavage.  Greenish,  crumpled  chloritic  plates  and  fibres,  forming  rosette- 
like  a.uuiv-atrs,  are  associated  with  the  garnet  as  an  alteration-product.  Also,  brownish 
plates,  with  the  strong  dichroisin  of  biotite,  were  seen.  Besides  the  secondary  chlorite 
and  biotite,  magnetite  and  hydrous  oxide  of  iron  have  been  produced  by  the  alteration  of 
the  garnet.  The  latter  mineral  is  next  in  abundance  to  the  oliviue,  and  in  its  fresh  state 
is  traversed  by  fissures.* 

Mod/iait <f,  Gusdals  See,  Norway, 

This  peridotite  is  stated  by  Mohl  to  be  formed  of  a  regular  mixture  of  olivine  grains, 
custatite  plates  with  some  grass-green  diopside,  and  chromite  grains  and  octahedrons. 
The  olivine  is  in  part  changed  to  serpentine,  but  in  general  it  is  water-clear  and  free  from 
pores  and  inclusions.  The  grains  often  show  a  grayish-yellow  ferruginous  tint,  and  the 
serpentinized  portions  are  composed  of  short  fibres,  causing  the  fissures  to  appear  broader, 
impellucid,  and  of  a  grayish-yellow  color. 

The  enstatite  is  in  single  scales,  which  are  numerous  and  of  a  nacarat  color. 

The  very  pellucid,  leek-green  chromdiopside  is  in  feebly  dichroic,  ledge-formed  pieces, 
filled  with  round  and  pipe-formed  glass  pores. 

The  ehromite  forms  rounded  grains  or  octahedrons  with  rounded  edges.  Portions  of 
these  grains  are  of  a  dark  hair-brown  color  when  viewed  by  transmitted  light. f 

Baste,  Harz. 

5062.  A  grayish-black  rock,  with  grayish-white  spots.  It  shows  the  characteristic 
schiller  of  the  enstatite  (bastite),  with  its  enclosed  olivine  grains.  Considerable  brown 
biotite  can  also  be  seen. 

Section :  dark  greenish-gray,  and  composed  of  an  irregular  sponge-like  mass  of  ensta- 
tite, diallage,  and  feldspar,  with  their  alteration-products,  holding  'rounded,  partially 
altered  olivines.  The  least  altered  olivines  are  traversed  by  numerous  fissures,  most  of 
which  extend  through  the  adjoining  pyroxene.  These  serve  as  channels  for  the  percolat- 
ing waters,  and  more  or  less  black  ferruginous  material  exists  in  them.  In  those  olivines 
that  are  further  changed  the  ferruginous  bands  increase,  and  a  greenish  serpentine  is 
observed  bordering  the  sides  of  the  fissures,  while  the  amount  of  clear,  unaltered  olivine 
between  the  meshes  made  by  the  fissures  grows  less.  Every  gradation  of  alteration  can  be 
observed  in  this  section,  from  that  above  mentioned  to  those  olivines  in  which  an  entire 
alteration  has  taken  place,  a  serpentine  mass  remaining,  which  shows  by  its  structure  and 
ferruginous  bands  the  former  fissure  lines  of  the  olivine.  In  some  highly  altered  portions 
a  few  grains  of  olivine  can  be  found,  a  mere  remnant  of  the  larger  grain  once  there.  The 
enstatite  and  diallage  are  traversed  by  numerous  cleavage  lines  and  fracture  planes,  which 
are  bordered  by  a  greenish  serpentine.  The  pyroxene  minerals  are  of  a  pale-yellowish 
tinge,  slightly  dichroic,  and  in  places  much  altered  to  the  serpentine.  The  feldspar  iu 
part  retains  the  characteristic  polysynthetic  twinning  of  plagioclase,  which  here  has  the 
same  lu-oad  banding  as  that  commonly  observed  in  the  feldspar  of  gabbros.  For  the  most 
part  it  is  altered  to  a  clear  or  gray  fibrous  mass,  with  brilliant  aggregate  polarization 
similar  to  that  of  liebenerite.  In  some  places  it  has  been  changed  to  a  dirty-green 
viriditii:  n 

Picotito  and  iron  ores  occur  in  the  mass  of  the  rock,  the  former  mineral  being  found 
*  Ncucs  Julir.  Min.,  1870,  pp.  230-232.  f  Nyt  Mag.,  1877,  xxiii.  117,  118. 


134  PERIDOTITE. 

even  in  the  feldspar.  A  little  brownish-biotite  was  observed  as  a  secondary  product. 
The  structure  of  a  portion  of  this  section  is  shown  in  figure  2,  Plate  VIII. 

Another  section,  purchased  from  Voigt  and  Hochgesang,  shows  similar  characters,  but 
part  of  the  olivine  and  enstatite  is  not  so  much  altered  as  in  the  preceding.  While  in 
the  former  the  diallage  largely  predominated,  in  this  only  enstatite  was  observed. 

A  section  of  so-called  serpentinfels  of  Baste,  purchased  from  R.  Fuess  of  Berlin, 
shows  a  gray  and  greenish-brown  sponge-like  mass  holding  serpentinized  olivines.  The 
general  structure  is  like  the  preceding  ones  described  from  Baste,  as  well  as  those  to  be 
later  given  from  Christiania  and  Gj$rud,  Norway,  but  the  alteration  lias  progressed  con- 
siderably further.  Talc  and  amphibole  occur  as  secondary  products,  as  does  a  pale  bluish- 
green  mineral  associated  with  a  mineral  of  pale  pinkish  or  grayish  color.  From  their 
association  and  relations  the  bluish-green  form  seems  to  be  a  better  developed  state  of 
the  gray  mineral.  Since  both  are  isotropic,  and  have  the  usual  structure  and  relations 
observed  belonging  to  garnet,  I  am  inclined  to  refer  them  to  that  mineral.  Associated 
with  these  are  coffee-brown  picotite  or  chromite  grains,  which  also  appear  to  be  of  second- 
ary origin,  and  closely  resemble  those  found  in  the  St.  Paul's  peridotite. 

No.  5041  is  another  specimen  of  the  so-called  schillerfels  from  Baste,  Harz,  obtained 
from  Voigt  and  Hochgesang.  This  is  a  greenish-black  rock,  showing  the  schiller  of  the 
altered  pyroxenes,  and  holding  rounded  grains  of  serpentinized  olivine.  Weathered  on 
one  side  to  a  rusty-brown.  The  section  of  this  is  very  similar  to  the  one  last  de- 
cribed,  but  contains  more  picotite,  and  none  of  the  pale  bluish-green  mineral  has  been  so 
far  observed. 

Streng  states  that  the  schillerfels  of  the  Harz  is  a  mixture  of  anorthite,  protobastite, 
diaclasite,  compact  schillerstein,  schillerspath,  serpentine,  and  chrome-bearing  magnetite.* 

Figure  1,  Plate  VIII.,  shows  a  portion  of  the  structure  of  an  enstatite  mass  with  its 
enclosed  olivines  —  the  characteristic  fissuring  of  both  minerals  being  shown.  The  dark 
grains  in  the  olivine  are  picotite  and  the  greenish  portion  indicates  the  beginning  of 
change  in  the  enstatite. 

Figure  2  of  the  same  plate  indicates  a  change  in  the  rock  still  further  advanced,  and 
shows  the  olivine  discolored  by  secondary  iron  ores  bordering  the  fissures,  and  more  or  less 
changed  to  serpentine,  while  the  enstatite  is  considerably  altered.  Figure  5  on  the  same 
plate  exhibits  a  phase  of  extreme  alteration,  the  rock,  while  retaining  its  structure,  having 
its  olivine  entirely,  and  its  enstatite  and  diallage  nearly,  if  not  entirely,  replaced  by  ser- 
pentine and  various  secondary  products. 

Christiania,  Nonvay. 

5063.  A  dark,  nearly  black  rock,  showing  in  places  the  schiller  of  the  pyroxene 
minerals,  and  occasionally  exhibiting  grayish-white  spots.  At  one  end  it  presents  an 
appearance  similar  to  that  of  the  forellenstein  of  Volpersdorf.  One  side  is  coated  with 
serpentine  and  dolomite. 

Section :  a  grayish-white  spongiform  mass,  enclosing  greenish,  serpentinized  olivines. 
The  olivine  is  much  altered,  showing  the  usual  reticulated  network  of  magnetite  with  the 
later  greenish  and  yellowish  serpentine.  Part  of  the  oliviue  enclosed  between  the  meshes 
remains  intact,  or  only  slightly  smoky.  In  some  of  these  elongated  tubes  of  minute  size 

«  Neues  Jahr.  Min.,  1862,  p.  521. 


THE  TERRESTRIAL   PERIDOTITES.  —  LHEfiZOLITE.  135 

occur   similar  to  those  observed  in  the  olivine  of   the  Siberian  pallasite  (ante,  p.  72). 
These  tubes  lie  parallel  to  the  plane  of  extinction  in  the  olivine. 

The  grayish-white  groundmass  is  composed  of  eustatite,  a  little  diallage,  and  various 
secondary  products.  The  enstatite  varies  from  a  clear  transparent  mineral  to  a  pale- 
brown  and  a  reddish-brown.  The  last  is  so  associated  with  the  first  as  to  indicate  that  it 
is  a  partially  altered  state  of  the  first.  This  reddish-brown  portion  owes  its  color  to  the 
same  included  plates  as  those  commonly  seen  in  bronzite  and  hypersthene  ;  and  it  could 
be  well  called  the  former,  or,  because  the  mineral  is  feebly  dichroic,  the  latter.  Whether 
the  altered  portions  of  the  groundmass  are  derived  in  part  from  the  alteration  of  feldspar 
or  entirely  from  the  pyroxene  minerals,  is  not  known.  No  distinguishable  feldspar  was 
seen.  The  pyroxene  minerals  are  in  part  changed  to  serpentine,  and  in  part  to  an  indefi- 
nite aggregately  polarizing  mass,  usually  surrounded  by  one  or  two  bands  of  secondary 
minerals  standing  perpendicular  to  the  bounding  surface.  The  outer  band  possesses  a 
polarization  similar  to  that  of  enstatite,  while  the  inner  resembles  an  amphibole  mineral. 
In  some  cases  on  the  olivine  side,  another  band  composed  of  serpentine  was  observed.  A 
similar  structure  frequently  exists  in  altered  gabbros,  but  in  this  case  the  products  are 
not  sufficiently  well  defined  to  be  determined.  Considerable  dolomite  was  seen  in  the 
more  highly  altered  portions  of  the  rock.  Altered  picotite  or  chromite  (slightly  translu- 
cent and  reddish-brown  in  spots),  as  well  as  iron  ore  produced  during  the  conversion 
of  the  olivine  into  serpentine,  was  found.  Only  a  small  portion  of  this  ore  remains  in 
the  parts  where  the  conversion  of  the  entire  oliviue  mass  is  most  complete. 

Figure  3,  Plate  VIII.,  shows  the  general  structure  of  this  rock.  The  white  portions 
ha>'e  the  granules  still  unchanged  in  the  greenish  secondary  serpentine  material,  which  in 
part  replaces  the  original  olivine.  The  brownish  portions  forming  a  matrix  for  the  altered 
olivine  are  the  enstatite  and  diallage,  which  for  the  most  part  are  changed.  The  bluish 
band  on  the  right  is  one  of  the  alteration-borders  between  the  olivine  and  enstatite. 

GJfinid,  Norway. 

This,  according  to  Mohl,  is  principally  composed  of  rounded  and  obtuse-angled  olivine 
grains,  which  form  from  sixty  per  cent  to  seventy  per  cent  of  the  mass. 

Along  the  contours  and  fissures  the  olivine  is  changed  to  a  bright  leek-green,  gray-green, 
and  grass-green  chrysotile,  whose  fine  fibres  are  arranged  partly  across,  and  partly 
parallel  to,  the  direction  of  the  veins.  The  centre  of  these  chrysotile  veins  is  generally 
filled  with  a  fine  black  line  of  magnetite  or  by  aggregations  of  magnetite  grains. 

Some  hypersthene  or  an  augitic  mineral  occurs  in  the  section.  This  is  dichroic,  of  a 
chocolate-brown  color,  but  altered  in  part  to  a  cloudy-grayish  and  yellowish-white  sub- 
stance, supposed  to  be  a  magnesium  carbonate.* 

In  a  section  of  Gj^rud  serpentine  purchased  from  R  Fuess,  a  gray,  sponge-like  mass  is 
seen  holding  the  greenish,  serpentiuized  olivine.  Excepting  that  the  alteration  has  pro- 
gressed some  further,  the  description  of  the  Christianin  peridotite  would  apply  to  this 
section.  If  the  dichroism  of  the  rhombic  pyroxene  arises  from  alteration,  as  I  suspect  it 
does,  there  seems  to  be  no  reason  for  calling  it  hypersthene,  instead  of  enstatite. 

Its  structure  and  alteration  are  shown  in  figure  4,  Plate  VIII. 

«  Nyt  Mag.,  1S77,  xxiii.  122,  123. 


136  PERIDOT1TE. 

Presque  Isle,  Michigan. 

65.  A  dark  grayish-black  to  black  rock,  showing  in  places  the  irregular  shimmer  of 
enstatite  holding  olivine. 

Section :  grayish-green,  and  composed  of  an  irregular  mass  of  enstatite,  olivine, 
diallage,  magnetite,  and  various  secondary  products  like  feldspar,  viridite,  dolomite,  ser- 
pentine, etc.  The  olivine  with  its  secondary  products  forms  in  places  the  principal 
portion  of  the  section ;  in  other  parts  the  enstatite  and  diallage  are  the  chief  minerals  ; 
while  the  olivine  and  magnetite  are  held  in  grains  in  the  interior.  The  olivine  crystals 
are  comparatively  large,  but  much  fissured  and  altered  along  the  fissures  and  exterior. 
The  interior  portions  are  clear  or  smoky,  except  where  the  olivine  material  has  been 
completely  changed.  The  alteration  shows  in  the  form  of  cloudy  bands  of  magnetite 
traversing  the  crystal  along  the  fissure  lines,  while  a  further  change  is  shown  by  the  for- 
mation of  greenisli  and  yellowish  serpentine  along  the  same  lines.  The  change  continues 
until  the  olivine  is  entirely  altered.  The  magnetite  usually  assumes  an  irregular  grating 
form  or  network  extending  through  the  serpentine,  as  well  as  being  arranged  in  lines 
which  show  the  former  position  of  the  olivine  fissures. 

The  enstatite  and  diallage  have  a  slight  tinge  of  green,  and  are  slightly  pleochroic. 
They  are  traversed  by  longitudinal,  transverse,  and  irregular  fissures,  the  latter  being  more 
abundant  in  part  of  the  diallage.  They  form  together  an  irregular  sponge-like  mass 
holding  olivine,  and  thus  present  a  structure  not  unlike  that  of  the  Atacama  and  Siberian 
pallasites,  in  which  they  play  the  r6le  of  the  iron.  They  seem  to  form  the  same  identical 
continuous  mass,  but  with  a  high  power  the  line  of  union  can  be  faintly  seen.  It 
probably  would  have  never  been  discovered  if  polarized  light  had  not  directed  attention 
to  it. 

The  enstatite  polarizes  with  a  pale  greenish  tint  differing  but  little  from  the  natural 
color,  while  the  diallage  shows  brilliant  hues  of  mixed  yellow,  red,  and  violet.  Both  are 
more  or  less  altered  along  the  fissures  to  a  greenish  or  a  yellowish-green  serpentinous 
product,  which  is  dichroic,  varying  from  a  green  to  a  yellowish-brown  shade.  Similar 
dichroisrn,  but  less  marked,  was  observed  in  the  serpentine  of  the  olivine.  In  the  highly 
altered  portions  of  the  section  are  lath-shaped  crystals,  branching  from  a  centre  in  a  fan- 
shaped  mass.  These  appear  to  be  feldspars,  some  of  which  possess  plagioclastic  characters. 
Associated  with  these  occur  brown  biotite,  a  little  apatite,  and  some  augitic  material.  The 
structure  of  these  patches  closely  resembles  that  of  some  diabases.  The  entire  section  is 
traversed  in  places  by  a  pale  greenish  serpentine  in  veins  holding  dolomite,  the  latter 
mineral  occurring  elsewhere  in  the  section.  Some  actiuolite  was  observed.  The  mag- 
netite is  in  octahedrons  and  irregular  grains,  as  well  as  in  the  secondary  forms  before 
mentioned.  The  cloudiness  of  the  olivine  seems  to  be  due  to  magnetite  granules. 

Besides  the  serpentine,  a  bluish-green  fibrous  viriditic  product  occurs,  associated  with 
brown  biotite  plates  in  such  a  manner  as  to  lead  to  the  belief  that  this  product  is  an 
earlier  stage  in  the  formation  of  biotite,  whicli  is  evidently  an  alteration  product  here. 
The  structure  of  the  enstatite  portion  is  shown  in  figure  3,  Plate  VII. 

73,  from  the  same  locality,  is  a  dark  grayish-black  to  black  rock,  mottled  with 
minute  specks  of  grayish-white,  as  well  as  with  pyrite.  Weathers  to  a  rusty  brown. 
Section :  of  a  dirty  green  color,  and  composed  principally  of  olivine  grains  and  crystals, 
with  magnetite  held  by  a  light  green  mass  of  enstatite,  diallage,  and  various  secondary 
products.  The  alteration  of  the  olivine  is  greater  here,  as  a  rule,  than  in  No.  65.  The 
magnetite  bands  along  the  fissures  are  wider,  and  fewer  portions  are  left  showing  the 


THE  TERRESTRIAL   PERIDOTITES.— LHERZOLITE.  137 

oliviue  polarization.  The  secondary  products  are  as  in  the  preceding,  but  more  abundant 
ami  well  marked.  Much  less  eiistatite  and  diallage  exist  here  than  in  No.  65,  and  they 
are  move  highly  altered.  The  interspaces  between  the  olivines  more  commonly  contain 
pule  greenish  serpentine,  bluish-green  and  yellowish  biotite  (?)  material,  dolomite,  mag- 
netite, etc.  Much  of  the  serpentine  shows  the  coarse  fibrous  laminae  so  commonly 
observed  in  the  serpentines  described  in  this  volume.  In  portions  of  this  section  and 
in  another  slide  from  the  same  hand  specimen  the  change  of  the  rock  mass  to  serpen- 
tine is  nearly,  and  sometimes  quite  complete,  the  forms  of  the  olivines  being  distin- 
guishable through  the  arrangement  of  the  magnetite  and  the  serpentine. 

The  general  structure  of  section  is  shown  in  figure  4,  Plate  VII. 

67,  from  the  same  locality,  is  composed  of  the  same  dark  grayish-black  rock,  which 
here  presents  a  brecciated  appearance  on  account  of  its  being  traversed  by  rambling  veins 
of  light-yellowish  serpentine.  In  the  section  the  rock  appears  as  a  dirty  greenish  mass 
traversed  by  greenish-white  veins.  It  is  composed  of  serpentine  pseudomorphs  of 
olivine,  filled  with  beautiful  dendritic  growths  of  magnetite,  as  well  as  with  irregular 
ma -sfs  of  the  same  mineral  The  interspaces  contain  the  various  secondary  products 
before  described  :  micaceous  (viriditic)  material,  serpentine,  magnetite,  feldspar,  dolomite, 
etc.  The  veins  are  composed  principally  of  dolomite  grains  and  serpentine,  the  former 
predominating. 

74,  from  the  same  locality,  is  much  like  No.  65,  but  the  grayish  spots  are  more 
abundant.  Under  the  microscope  it  is  seen  to  be  composed  of  a  coarsely  fibrous  lamellar 
serpentine  traversed  by  the  irregular  network  of  magnetite  so  common  in  the  serpen- 
tinized  peridotites.  It  contains  a  little  dolomite  and  one  plate  of  a  micaceous  mineral 
was  observed.  This  was  feebly  dichroic,  greenish  and  yellowish,  extinguished  parallel 
to  the  nicol  diagonal,  and  polarized  with  a  beautiful  purplish-blue  tint.  It  presents  a 
fine  micaceous  cleavage  parallel  to  the  line  of  extinction,  and  it  is  probably  partially 
formed  biotite. 

71,  from  the  same  locality,  is  a  grayish-green  rock  traversed  by  grayish-white  veins  of 
dolomite,  which  give  to  it  a  rude  appearance  of  foliation.  The  rock  contains  a  number 
of  reddish-brown  patches  formed  from  a  breccia  of  the  decomposed  rock  held  by  minute 
reticulated  veins  of  dolomite.  The  section  is  composed  of  yellowish  and  bluish  green, 
and  reddish-brown  pseudomorphs  of  oliviue  held  in  a  granular  mass  of  dolomite. 
Crystals  and  grains  of  magnetite  are  scattered  throughout  the  rock.  The  olivine  in  the 
greenish  pseudomorphs  has  been  entirely  replaced  by  serpentinous  and  ferruginous 
material  with  dolomite,  the  first  predominating.  The  reddish-brown  pseudomorphs  have 
the  ferruginous  material  the  most  prominent,  and  it  is  these  pseudomorphs  which  form 
the  reddish- brown  patches  before  referred  to.  The  fissures  of  the  olivine  are  represented 
by  ferruginous  and  sometimes  by  dolomitic  bands,  and  these  bands  can  sometimes  be 
seen  in  the  dolomite,  showing  the  form 'of  the  pseudomorph  when  the  latter  has  been 
almost  entirely  replaced  by  dolomite.  A  portion  of  the  structure  of  the  section  is  shown 
in  figure  5,  Plate  VII. /the  gray  groundmass  being  dolomite  and  the  greenish  patches  the 
paeudomorphs  after  olivine. 

69,  from  tin;  same  locality,  is  a  pale  oil-green  serpentine,  banded  and  spotted  with 
dark  and  light  brown.  The  section  is  composed  of  a  granular  and  fibrous  mass  of 
si-i|>rntine  and  dolomite,  with  ferruginous  and  earthy  material,  all  holding  brownish- 
yellow  uarthy  pseudomorphs  after  olivine,  which  are  traversed  by  the  ferruginous  Viands 
rejnvseiiting  the  olivine  fissures.  These  pseudomorphs  are  wanting  in  portions  of  the 
section.  Much  of  the  serpentine  shows  the  fine  fibrous  polarization  of  chrysotile. 

18 


138  PERIDOTITE. 

66,  from  the  same  locality,  is  a  dark  greenish-brown  rock  traversed  by  a  network  of 
oil-green  serpentine  veins,  giving  it  a  roughly  foliated  appearance.  The  section  is  very 
similar  in  character  to  that  of  the  preceding. 

70  is  a  dirty  green  rock  coining  from  the  upper  portion  of  the  mass  at  Presque  Isle. 
Section  grayish,  and  composed  principally  of  a  granular  mixture  of  dolomite  and  serpen- 
tine with  some  ferruginous  and  micaceous  materials,  etc. 

72  is  from  a  portion  of  the  Presque  Isle  peridotite  which  has  been  so  filled  by 
dolomitic  material  as  to  form  a  vein.  The  rock  is  brownish-gray  with  a  slight  pinkish 
tinge,  and  composed  of  granular  dolomite  holding  masses  and  grains  of  the  decomposed 
peridotite.  It  presents  the  usual  structure  observable  in  veins  formed  by  the  decom- 
position and  the  partial  removal  of  the  original  rock,  and  its  replacement  by  vein 
material.  This  more  properly  comes  later,  in  the  portion  of  this  work  in  which  the  vein- 
stones are  described  ;  but  on  account  of  its  connection  with  the  previously  described  peri- 
dotite it  is  given  here.  The  sections  are  composed  of  a  dirty  gray  granular  dolomite, 
holding  patches  of  ferruginous  material,  both  dark  and  light  yellowish-brown.  In  places 
the  darker  portions  show  the  cherry-red  color  of  hematite,  and  appear  in  part  at  least  to 
replace  olivine. 

The  Presque  Isle  peridotite  was  microscopically  studied  by  Dr.  A.  Wichmann,  who 
gave  a  short  description  of  it  under  the  name  serpentine,  stating  that  it  consisted  only  of 
olivine,  serpentine,  and  magnetite.*  No  chromite  was  found,  on  making  proper  tests, 
in  the  Presque  Isle  rock,  either  by  Professor  Whitney  f  or  myself  ;J  but  Dr.  Eominger 
states  §  that  it  contains  two  per  cent  of  chromic  iron  in  small  octahedrons  readily  attracted 
by  the  magnet,  although  he  does  not  remark  whether  this  iron  was  tested  to  prove  the 
presence  of  chromium  or  not. 

This  peridotite  is  confidently  believed  to  be  eruptive  from  the  following  observed  evi- 
dence. On  the  southeastern  side  the  overlying  Potsdam  sandstone  dips  quite  irregularly 
from  twenty  to  thirty  degrees  southerly.  Its  strata  follow  continuously  the  curve  of  the 
underlying  peridotite,  and  even  in  places  form  anticlinals.  The  surface  of  the  peridotite 
is  an  irregular  knobby  one,  while  it  forms  as  a  whole  an  immense  knob.  To  this  knobby 
structure  the  layers  of  the  sandstone  conform  continuously,  as  layers  of  blankets  would, 
and  they  show  no  signs  of  deposition  against  or  around  the  knobs,  but  rather  a  structure 
as  if  the  sandstone  layers  had  themselves  been  indented  and  bent  by  the  peridotite  itself. 
The  sandstone  with  its  conglomeritic  portion  for  some  two  or-  three  feet  above  the  perido- 
tite has  been  greatly  indurated  and  changed,  showing  heat  action,  particularly  that  of 
thermal  waters.  It  is  filled  with  vein  and  clialcedonic  quartz ;  and  indurated  and  red- 
dened as  such  rocks  are  known  to  be  when  in  contact  with  eruptives  of  later  date  than 
themselves.  These  indurated  portions  show,  on  examination  under  the  microscope,  that 
much  of  the  quartz  is  a  secondary  water  deposit  formed  since  the  deposition  of  the  frag- 
ments composing  the  rock.  Above  this  indurated  portion  comes  the  ordinary  unaltered 
sandstone.  No  fragments  of  the  peridotite  could  be  found  macroscopically  in  the  field  or 
microscopically  in  the  laboratory  in  the  sandstone.  Now  the  sandstone  does  not  hold 
such  relations  to  the  Azoic  rocks  of  the  district  when  in  contact  with  them,  and  it  seems 
right  to  maintain  that  this  peridotite  is  younger  and  an  eruptive  rock,  intruded  in  the 
form  of  a  laccolite  since  the  Potsdam  sandstone  was  laid  .down.|| 

*  Geol.  Wise.,  18SO,  iii.  618.  f  Am.  Jour.  Sci.,  1859,  xxviii.  IS. 

J  Bull.  Mus.  Comp.  Zool.,  1880,  vii.  61.  §  Geol.  Mich.,  1881,  iv.  136. 

||  See  Foster  and  Whitney,  Geology  of  Lake  Superior,  1851,  ii.  17,  18,  92,  121,  122  ;  Bull.  Mus.  Comp. 
Zool.,  1880,  vii.  2,  3,  6,  9,  10,  23,  60-66. 


THE   TERRESTRIAL   PERIDOTITES.  —  LHERZOLITE.  139 

Sec.  29,  T.  48,  R.  27.     Three  and  one-half  miles  northwest  of  Ishpeming, 

Michigan. 

242.  A  gray,  somewhat  fibrous  rock.     Section:  a  gray  mass  traversed  by  a  network 
of  magnetite.     It  is  composed  of  a  light  gray  and  colorless  transparent  mass  of  serpentine 
with  some  dolomite,  and  has  the  usual  reticulated  arrangement  of  the  magnetite  so  char- 
acteristic of  the  serpentines  produced  from  the  alteration  of  olivine  rocks. 

241,  from  the  same  locality,  is  a  greenish-  and  reddish-brown  rock  traversed  by  green- 
ish-gray serpentine  veins.  Weathers  light  yellowish-green.  The  reddish-brown  color  is 
owing  apparently  to  a  ferruginous  staining  of  the  serpentine  folise.  Section  is  brownish- 
gray  and  composed  of  a  pale  greenish-yellow  serpentine  traversed  by  irregular  reticulated 
magnetite  bands,  and  spotted  by  irregular  ferruginous  stains  of  reddish- and  brownish-yellow. 
While  in  the  hand  specimen  these  stains  present  the  appearance  of  distinct  micaceous 
folia*,  I  ain  unable  by  the  microscope,  either  in  common  or  polarized  light,  to  find  any 
structure  peculiar  to  them  and  distinct  from  the  serpentine,  beyond  that  belonging  to 
ordinary  ferruginous  stains.  The  serpentine  shows  an  irregular  fibrous  and  lamellar 
structure  in  polarized  and  common  light. 

245,  from  the  same  locality,  is  similar  to  the  preceding.  Its  staining  is  deeper,  and 
the  rock  is  coated  on  one  side  with  a  chrysotile  and  dolomite  vein.  In  the  section  the 
fibrous  structure,  the  magnetite  network,  and  the  ferruginous  staining  are  all  more 
strongly  marked  than  in  the  preceding. 

243,  from  the  same  locality,  is  a  greenish-gray  rock  with  the  ferruginous  staining 
showing  in  a  few  spots  only,  —  principally  along  fissures.     The  section  is  gray,  and  under 
the  microscope  is  seen  to  be  composed  of  pale  greenish -yellow  serpentine  with  cloudy 
spots.     These  appear  to  be  occasioned  by  a  fine  magnetite  dust,  which  is  generally  associ- 
ated with  an  approach  to  crystallization  on  the  part  of  the  surrounding  material,  which 
somewhat  affects  polarized  light.     Numerous  pale  greenish  scales  occur  in  abundance  in 
the  serpentine,  and  have  the  polarization  characters  of  talc.     Crystals  and  grains  of  mag- 
netite are  scattered  throughout  the  section. 

235,  from  the  same  locality,  is  a  clear  translucent  green  serpentine  containing  magne- 
tite grains.  It  weathers  light-colored,  even  to  a  chalky-white.  The  section  forms  a  clear 
almost  colorless  mass  spotted  with  crystals  and  grains  of  magnetite.  The  same  mineral 
also  traverses  the  section  in  the  form  of  a  vein.  In  common  light  the  clear  serpentine 
mass  shows  fibrous  structure,  which  is  beautifully  brought  out  in  polarized  light.  The 
magnetite  appears  as  a  secondary  product 

Associated  with  these  are  other  specimens  of  greenish-  and  reddish-brown  serpentine 
often  traversed  by  dolomite  veins.  In  large  masses  this  dolomitic  material  with  talc 

oa  to  have  replaced  nearly  all  of  the  serpentine,  giving  rise  to  a  rock  called  locally 
limestone.  Much  chrysotile  also  occurs.* 

Transylvania,  Austria. 

Tschermak  describes  a  schillerfels  f  from  this  region  as  a  dark-green  rock  with  white 
spots  composed  of  olivine,  bronzite,  diallage,  magnetite  or  chromite,  and  a  little  anorthite. 

*  See  further,  Bull.  Mus.  Comp.  Zool.,  1880,  vii.  05,  66 ;  Wright,  Mineral  Statistics  of  Michigan,  1879, 
pp.  201-200;  Romin-rer,  Geol.  Michigan,  1881,  iv.  137-143. 

t  Herbich  appears  to  class  this  with  eruptive  rocks.  Verh.  Mitth.  Natur,  Hermaunstadt,  1865,  xvi. 
173-183. 


140  PEEIDOTITE. 

The  olivine  is  traversed  by  a  network  of  dark-green  serpentine  fibres,  and  the  diallage  and 
bronzite  are  both  somewhat  altered.  Associated  is  a  compact  dark-green  serpentine  hold- 
ing some  chysolite  and  chromite.  Another  rock  from  the  same  district  is  of  a  dark  olive- 
green  color,  flecked  with  white  spots  ;  and  contains  a  platy  greenish-brown  shining  diallage, 
a  deep  green  finely  granular  mass  of  olivine,  and  small  white  grains  of  anorthite.  The 
olivine  is  here  traversed  by  a  network  of  dark-green  serpentine.* 

Fitchtelgebirge,  Bavaria. 

These  rocks  are  composed  principally  of  olivine  with  enstatite,  chromdiopside,  augite, 
and  magnetite.  The  olivine  is  more  or  less  altered  into  a  serpentine,  showing  the  usual 
network  structure.  The  enstatite  is  in  elongated,  fibrous,  brilliant  clear  wine-green 
needles,  and  the  chromdiopside  in  roundish,  compact,  somewhat  fissured  particles.  The 
groundmass  consists  of  a  mixture  of  chlorite,  serpentine,  etc.f 

A  Pebble  from  the  Jaina  River,  ten  to  twelve  miles  N.  W.  of  Ml.  Mariana,  C/iico, 
Prov.  San  Domingo,  San  Domingo. 

252  G.  A  compact  dark-green  groundmass  holding  crystals  of  brownish  pyroxene 
and  traversed  by  veins  of  chromite. 

Section :  a  gray  groundmass  holding  iron  ore  and  crystals  of  enstatite  and  diallage. 
The  groundmass  is  composed  almost  entirely  of  clear  beautifully  polarizing  serpentine, 
which  shows  in  its  structure  traces  of  the  bounding  planes  of  the  minerals  from  whose 
alteration  it  was  derived.  A  little  white  plagioclase,  traversed  by  cleavage  planes,  was 
observed,  portions  of  which  had  been  rendered  gray  and  nearly  opaque  by  kaolinization. 
Only  a  few  small  fissured  olivine  grains  were  observed.  The  enstatite  and  diallage  can 
here  as  a  rule  be  distinguished  by  their  cleavage,  the  latter  being  much  less  regular  than 
the  former,  and  closely  like  that  of  augite.  Both  are  in  irregular  grains,  more  or  less 
altered  to  a  greenish-  and  yellowish-brown  product.  Where  the  change  has  progressed 
far,  the  ordinary  serpentine  of  the  groundmass  is  the  result.  Sometimes  the  serpentine 
resulting  is  filled  with  minute  black  globules,  or  with  minute  microlitic  forms,  ar- 
ranged in  lines  forming  definite  angles  with  one  another.  The  iron  ore  is  in  part  in 
crystals  and  part  in  irregular  grains  and  masses.  The  structure  is  shown  in  figure  6, 
Plate  IV. 

This  rock  was  collected  by  Professor  W.  M.  Gabb. 

Starkenbach,  Bluttenberg,  Vosges,  Frame. 

According  to  Weigaud  this  is  soft  black  rock  containing  brownish-yellow  and  brass- 
yellow  crystals.  In  the  thin  section  the  rock  is  seen  to  be  composed  of  bronzite  (ensta- 
tite), diallage,  olivine,  magnetite,  hornblende  (smaragdite  ?),  and  picotite,  with  more  or 
less  serpentine.  The  enstatite  and  olivine  are  more  or  less  traversed  by  fissures  filled 
with  serpentine.  The  hornblende  is  in  minute  plates,  while  the  bronzite  is  the  predomi- 
nating mineral.^ 

*  Site.  Wien.  Akad.,  1867,  Ivi.  261-274. 

f  C.  W.  Gumbel,  Die  palaolitliischeu  Eruptivgesteiue  des  Fichtelgebirges,  1874,  pp.  38-41. 

}  Miu.  Mitth.,  1S75,  pp.  192-196. 


THE   TERRESTRIAL   PERIDOTITES.  —  LHERZOLITE.  141 

Todtmoos,  Baden. 

5000.  The  specimen  from  this  locality  in  the  collection  is  a  blackish-green  compact 
one,  containing  a  ff\v  disunite  and  diallage  crystals.  It  weathers  to  an  earthy  rusty- 
brown,  showing  the  network  method  of  decomposition  frequently  observed  in  the  perido- 
tites.  This  with  the  sections  was  purchased  from  Voigt  and  Hochgesang,  Gottingen. 

One  section  has  a  greenish  groundmass  holding  crystals  and  grains  of  enstatite,  dial- 
lage, olivine,  and  picotite.  The  enstatite  is  in  part  clear  and  unaltered,  holding  picotite 
grains,  and  in  part  it  has  suffered  a  greenish  and  yellowish  serpentinous  alteration.  The 
same  can  be  stated  of  the  diallage.  Both  are  in  rounded  crystals  and  irregular  masses, 
and  show  the  usual  cleavage  lines. 

The  olivine  when  unchanged  is  in  clear  grains,  the  remnants  of  the  original  larger 
crystals  ami  grains.  That  a  series  of  these  grains  now  separated  by  the  serpentine  bands 
once  formed  the  same  crystalline  mass,  is  shown  conclusively  by  their  possessing  the  same 
optical  orientation.  The  major  portion  of  the  original  olivine  has  been  changed  to  ser- 
pentine, the  structure  showing  the  successive  stages  of  alteration.  The  serpentine  formed 
first  along  the  fissures  has  a  dividing  line  indicating  the  fissure,  and  on  both  sides  the  ser- 
pentine fibres  stand  at  right  angles  to  that  line.  The  color  of  this  serpentine  is  generally 
a  light  yellowish-green.  The  interior  portion  occupying  the  interspaces  left  between  the 
network  lines  above  described,  is  occupied  by  serpentine  of  a  different  shade  of  green, 
sometimes  lighter,  sometimes  darker.  This  serpentine,  which  replaces  the  olivine  grains 
before  described,  shows  not  only  by  its  color,  but  also  by  its  structure,  both  in  common 
and  iu  polarized  light,  that  it  possesses  a  distinct  organization  from  that  of  the  network, 
and  is  distinctively  a  later  product.  The  serpentine  forms  the  chief  portion  of  the 
groundmass  and  is  feebly  dichroic.  While  it  is  usually  of  some  shade  of  yellowish-green 
to  pale-green,  in  some  cases,  especially  about  the  ferruginous  products,  it  is  of  a  bluish- 
green  color,  doubtless  owing  to  the  ferrous  oxide.  Some  secondary  actinolite  and  talc 
exist  associated  witli  the  pyroxene  minerals.  The  picotite  is  in  coffee-brown  and  pale- 
greenish  irregular  grains  scattered  throughout  the  section  in  the  different  minerals.  The 
larger  grains  along  their  fissures  and  edges  are  altered  to  a  black  ferruginous  product, 
probably  chromite.  This  alteration  sometimes  extends  nearly,  and  sometimes  quite, 
through  the  entire  picotite  grain.  Considerable  secondary  iron  ore  exists,  which  is  either 
chromite  or  magnetite. 

Another  section  has  a  yellowish-green  groundmass  containing  grains  of  enstatite, 
diallage,  and  picotite,  and  traversed  by  veins  of  talc.  The  groundmass  is  a  network  of 
serpentine  of  a  pale  yellowish-green  color,  surrounding  portions  of  a  deeper  green  repre- 
senting the  unfissured  parts  of  the  olivine,  while  the  meshes  follow  the  fissures.  The 
enstatite  and  diallage  are  in  places  only  slightly  altered ;  but  for  the  most  part  they  are 
traversed  by  threads  of  the  serpentine  web,  and  possess  a  fibrous  alteration-structure 
showing  a  more  or  less  .aggregate  polarization ;  yet  iu  the  majority  of  cases  they  retain 
their  relative  extinction.  This  serpentine  is  very  beautiful  in  polarized  light.  The  pico- 
tite is  in  irregular  fissured  grains,  sometimes  opaque,  but  more  commonly  with  dark 
brown  to  black  edges,  and  with  a  light  brown  to  dark  reddish-brown  interior.  Much 
ferruginous  material  in  grains  and  irregular  patches  is  distributed  through  the  section. 

This  serpentine  has  been  referred  by  Ilosenbusch  to  the  Iherzolites. 


142  PERIDOTITE. 

From  Spur  between  Deadwood  and  Poker  Flat,  Cal. 

Ill  P.  A  dark-yellowish  and  brownish-green  rock  containing  enstatite  grains  and 
talc  scales ;  and  traversed  by  light-greenish  serpentine  veins.  Section :  a  greenish-gray 
mass  flecked  with  magnetite  grains  and  traversed  by  a  grayish-yellow  serpentine  vein. 
The  chief  portion  of  the  section  is  serpentinous  material,  in  which  besides  the  magne- 
tite are  scattered  the  remains  of  enstatite  crystals  and  a  few  grains  of  olivine  and  diallage. 
The  serpentine  varies  in  color  from  white  to  yellowish  and  green.  In  places  clear  white 
leaves  of  talc  associated  with  magnetite  occur ;  while  some  hematite  is  to  be  seen.  Along 
the  sides  of  the  serpentine  vein  before  mentioned  the  section  is  black  with  the  rejected 
magnetite.  Much  of  the  enstatite  contains  the  same  inclusions  that  the  bronzite  variety 
is  accustomed  to  hold. 

The  structure  is  shown  in  figures  3  and  6,  Plate  VI. 

Levanto,  Italy. 

One  specimen  described  by  Prof.  T.  G.  Bonney  from  this  locality  is  a  purplish- 
or  brownish-black  rock  veined  occasionally  with  dull  green,  and  flecked  with  crystal- 
line folia  of  glittering  bronzite,  while  another  specimen  is  of  a  more  granular  texture, 
greener  color,  and  rougher  fracture  than  the  preceding,  but  otherwise  similar.  The 
second  rock,  in  the  thin  section,  is  seen  to  consist  chiefly  of  olivine  grains  separated  by 
threads  of  serpentine.  It  contains  opacite,  enstatite,  augite,  and  perhaps  a  little  diallage. 
Opacite  [magnetite]  occurs  in  the  enstatite  and  a  little  picotite  was  observed. 

The  first  specimen  was  seen  under  the  microscope  to  have  been  completely  altered,  no 
olivine  remaining  intact.  Much  opacite  was  found,  which  often  forms  continuous  strings, 
and  is  present  to  a  greater  or  less  extent  in  the  grains  that  were  formerly  olivine.  It 
forms  bauds  towards  the  exterior  of  the  grains,  or  is  disseminated  throughout  them. 
Diallage  and  enstatite  are  both  present,  the  latter  being  surrounded  by  a  border  of  a  ser- 
pentinous mineral,  into  which  are  continued  the  principal  cleavage  planes,  often  marked 
by  opacite  lines.  Thin  bands  of  serpentine  indicate  the  prismatic  cleavage.* 

Near  Limni,  Euboea. 

A  black  splintery  rock,  which,  as  described  by  Becke,  contains  lustrous  bronze-colored 
grains  of  enstatite.  Under  the  microscope  it  shows  the  evident  maschenstruTctur  of  the 
serpentine  which  holds  lens-forrned  masses  of  fresh  olivine.  This  groundmass  porphy- 
ritically  contains  fresh  enstatite  of  a  pale  brownish  color  and  a  marked  fibrous  texture. 
This  mineral  is  sometimes  altered  to  a  feeble  bluish  polarizing  product.  This  alteration 
extends  from  the  exterior  along  the  fissures  towards  the  interior.  Diallage,  reddish- 
brown  octahedrons  of  picotite,  and  secondary  magnetite  also  occur. 

Similar  to  this  is  a  rock  from  Mantoudi,  in  the  northern  portion  of  Eubrea.  This  is 
brownish,  and  contains  numerous  plates  of  enstatite  in  a  fine-grained  groundmass.  No 
diallage  was  observed,  but  the  brownish  color  of  the  rock  is  due  to  brown  hydrated 
oxide  of  iron. 

Similar  to  this  is  a  rock  from  the  district  of  middle  Eubrea,  between  Chalcis  and- 
Gides,  which  has  a  reddish-brown  groundmass  holding  tombac-brown  eustatite  (bastite). 
No  olivine  remains  unaltered  to  serpentine. 

*  Geol.  Mag.,  1879  (2),  vi.  362-371. 


THE  TERRESTRIAL   PERIDOTITES.  —  LHERZOLITE.  143 

A  rock  of  similar  character  was  obtained  between  Kuini  aud  Kastrovolo,  in  middle 
Eubcjca,  possessing  diallage  instead  of  enstatite.  The  diallage  is  partly  altered  into  a 
greenish  substance  and  partly  into  talc  plates. 

A  serpentine  from  Kami  was  found  to  contain  much  chromite,  magnetite,  and  some 
green  ouvarovite.* 

Oberlaitf,  Luzon,  Philippine  Islands. 

A  dark  blackish-green  serpentine-like  compact  rock,  with  crystals  of  clear  green  dial- 
lage and  brownish  enstatite.  The  principal  cleavage  planes  show  a  mother-of-pearl 
lustre.  Microscopically  the  rock  possessed  the  usual  mesh  structure,  and  contained  mag- 
netite and  picotite.f 

Lizard  District,  Cornwall. 

The  serpentines  of  this  district  were  found  to  present  intrusive  relations  to  the 
adjoining  rocks  by  Prof.  T.  G.  Bonney.  They  send  tongues  and  dikes  into  the  latter  and 
hold  included  fragments  of  them,  while  the  adjacent  rocks  at  their  junction  with  the 
serpentine  were  oftan  altered  and  contorted.  The  microscopic  examination  indicated  that 
the  serpentine  resulted  from  the  alteration  of  Iherzolite.  The  following  is  condensed 
from  Professor  Bonney's  description  of  the  rocks  and  sections.  The  rock  from  Coverack 
Cove  is  a  dull  mottled,  red  and  green  rock  with  flakes  of  a  silky  bronzitic  mineral  in  the 
green  portion.  Under  the  microscope  the  serpentine  forms  golden-colored  and  reddish- 
aud  greenish-brown  reticulated  veins,  which  enclose  colorless  olivine,  as  well  as  augite, 
enstatite,  and  diallage.  Original  and  secondary  iron  ores  occur.  A  rock  from  Mullion 
Cove  has  a  similar  composition  and  structure,  but  the  alteration  of  the  olivine  has  pro- 
gressed further,  with  a  differentiation  of  the  common  black  ferruginous  dust  A  few 
small  grains  resemble  picotite. 

At  Gue  Graze  a  similar  but  more  decomposed  rock  was  obtained,  which  appeared  to 
contain  a  pseudomorphic  product  after  feldspar.  From  the  Lower  Pradanach  and  the  Rill 
quarries  similar  rocks  to  that  from  Mullion  Cove  were  obtained,  but  in  one  from  Helston 
Uoad  a  little  hornblende  was  observed. 

The  rock  from  Goomhilly  Downs  is  a  banded  dull-colored  light-greenish  serpentine, 
containing  in  the  section,  besides  the  serpentine,  olivine,  hornblende,  magnetite,  and  some 
picotite.  A  number  of  other  sections  were  examined,  but  they  are  mainly  similar  to  the 
above,  or  else  have  been  more  highly  altered,  so  that  the  olivine  was  entirely  changed ; 
but  the  reader  is  referred  to  the  original  paper  for  the  particulars.^ 

Two  other  areas  of  serpentine  were  later  examined  in  the  Lizard  district,  one  of  which 
shows  excellent  junctions  and  is  clearly  intrusive  in  the  associated  schist.  Bonney  also 
re-examined  the  other  portions  of  the  district  previously  studied  by  him,  and  found  the 
strongest  evidence  of  the  intrusion  of  the  serpentine  into  the  associated  sedimentary 
rock.  § 

From  the  Troad,  Asia  Minor. 

Owing  to  certain  arrangements,  and  for  a  consideration,  the  lithological  collection  of 
the  Assos  expedition  has  become  the  property  of  Professor  Whitney,  and  passed  over  to 

*  Min.  Mitth.,  1878  (1),  i.  477-485. 

f  Konrad  Oebbeke,  Neues  Jalir.  Min.,  Beilage  Band,  1882,  i.  499. 

J  Quart.  Jour.  Geol.  Soc.,  1877,  xxxiii.  884-928  ;  1883,  xxxix.  21-23. 

§  Phil.  Mag.,  1882  (5),  xiv.  478  ;  Quart.  Jour.  Geol.  Soc.,  1883,  xxxix.  21-23. 


144  PERIDOTITE. 

ray  charge.  Mr.  Diller  (who  collected  the  specimens)  has  kindly  consented  that  I  should 
use  his  written  description  of  the  Assos  serpentine  rocks,  not  yet  published  except  in  ab- 
stract,* and  it  is  given  below,  with  a  few  verbal  changes  to  adapt  it  to  the  present  work. 

"  Serpentine  occurs  in  the  Troad  at  Qara-dagh  .  .  .  derived  from  the  alteration  of 
eruptive  rocks ;  also  about  the  summit  of  Mt.  Ida  in  small  lenticular  masses  in  talcose 
schist,  and  belongs  to  the  stratified  rocks;  also  .  .  .  forming  low  rounded  conical  hills 
near  the  base  of  Qara-dagh.  The  rock  is  usually  of  a  deep  green  color,  but  varies, 
becoming  bluish  or  reddish,  often  presenting  smooth  fibrous  surfaces  like  slickensides, 
and  occasionally  an  imperfect  columnar  structure.  Although  locally  uniform,  it  is  gen- 
erally made  porphyritic  by  a  fibrous  or  lamellar  mineral,  whose  cleavage  plates  between 
crossed  nicols  show  an  acute  bisectrix  with  the  plane  of  the  optic  axes  at  right  angles 
to  the  fibrous  structure.  The  mineral  is  bastite,  and  in  all  probability  has  been  produced 
by  the  alteration  of  enstatite. 

"  Under  the  microscope  the  composition  of  the  rock  is  seen  to  vary  greatly.  Sometimes 
it  is  composed  almost  wholly  of  a  network  of  serpentine  containing  a  few  grains  of  unal- 
tered olivine,  bastite,  and  much  iron  ore.  In  other  cases  the  serpentine  is  a  subordinate 
constituent,  and  olivine  forms  the  chief  mass,  in  which  are  imbedded  enstatite,  for  the 
most  part  changed  to  bastite,  and  also  very  rarely  a  colorless  mineral,  with  prismatic  and 
pinacoidal  cleavage.  It  appears  to  belong  to  the  pyroxene  group,  but  with  the  few  sec- 
tions present  its  optical  relations  could  not  be  determined.  It  is  evident  that  the 
serpentine  of  Qara-dagh  is  derived  from  an  olivine  enstatite  rock. 

"  In  the  Kemar  Valley,  a  short  distance  east  of  where  it  opens  into  the  Trojan  Plain, 
loose  blocks  of  serpentine  containing  numerous  very  bright  silvery  crystals  of  bastite  have 
been  observed.  In  the  thin  section,  besides  serpentine,  olivine,  enstatite,  bastite,  and 
irregular  dark  grains,  there  occur  numerous  small  black  crystals  whose  square  rhombic 
and  hexagonal  sections  indicate  that  they  may  belong  either  to  spinel  or  magnetite ;  but 
as  they, are  not  translucent,  they  are  most  likely  magnetite. 

"  Further  up  the  valley  the  serpentine  is  indistinctly  porphyritic,  and  occurs  inti- 
mately associated  with  schists  and  crystalline  limestone,  through  which  it  appears  to  pene- 
trate in  the  form  of  irregular  dikes.  Its  specific  gravity  is  2.593.  The  microscopical 
structure  of  these  rocks  is  strongly  contrasted  with  that  of  the  serpentine  from  Qara- 
dagh.  Between  crossed  nicols  they  appear  rather  coarsely  microcrystalline,  and  through- 
out the  greater  portion  of  the  section  are  not  only  uniform,  but  show  no  trace  of  the 
characteristic  reticulated  structure  of  serpentine  derived  from  the  alteration  of  olivine.f 
However,  here  and  there  a  few  meshes  of  the  old  net  are  still  preserved,  and  there 
appears  to  be  a  passage  from  this  portion  into  the  other,  in  which  the  same  structure  can- 
not be  traced.  The  porphyritic  crystals,  as  in  the  other  cases,  are  bastite,  with  considerable 
quantities  of  carbonates.  According  to  Mr.  Frank  Calvert  the  serpentines  in  the  vicinity 
of  the  Kernar  Valley  occur  as  distinct  dikes  cutting  the  crystalline  limestones,  so  there 
can  be  no  doubt  concerning  their  eruptive  nature,  and  they  are  in  all  probability  derived 
from  olivine  enstatite  rocks. 

"  Near  the  centre  of  Mt.  Ida  the  oldest  rocks  crop  out,  and  among  them  are  talcose 
schists,  which  by  the  addition  of  olivine  pass  into  small  lens-shaped  masses  composed 

*  Papers  of  the  Archaeological  Institute  of  America,  Classical  Scries,  i.  201,  203 ;  Science,  1883,  ii. 
255-258. 

f  Hussak,  after  studying  microscopically  a  numher  of  Alpine  serpentines,  concluded  that  in  the  ser- 
pentines derived  from  schistose  rocks  the  characteristic  reticulated  structure,  chromite,  and  picotite  are 
wanting. 


THE  TERRESTRIAL   PERI  DOT  ITES.  —  LHERZOLITE.  145 

almost  exclusively  of  the  latter  mineral.  According  to  the  nomenclature  of  Brogger,  the 
rock  of  these  patches  should  be  called  olivine  schist.  By  alteration  it  gives  rise  to  ser- 
pent inu  with  the  characteristic  reticulated  structure  which  ever  marks  the  serpentine  de- 
rived from  olivine.*  Occasionally  the  fibrous  serpentine  forms  veins  of  considerable  size 
in  the  adjacent  rocks.  The  olivine  schist  when  purest  has  no  schistose  structure.  The 
passage  from  pure  talc  schist  in  which  no  olivine  occurs  to  that  composed  almost  completely 
of  olivine,  takes  place  sometimes  within  a  short  distance.  The  chief  mass  of  the  rock,  how- 
ever, is  a  middle  stage  between  the  two  extremes,  having  a  distinct  schistose  structure  and 
composed  for  the  most  part  of  olivine  and  talc,  besides  considerable  quantities  of  pyroxene 
as  well  as  other  minerals  not  yet  determined." 

Differing  in  some  points  from  Mr.  Diller,  although  agreeing  with  him  in  the  main,  it 
lias  seemed  best  to  add  more  special  descriptions  of  the  individual  rocks  and  sections  in 
question.  It  is  further  necessary  to  do  this  in  order  to  point  to  the  gradations  and  altera- 
tions which  are  conspicuous  in  them.  Part  appear  to  belong  to  the  Iherzolite  variety, 
•while  others  are  so  far  altered  that  it  cannot  be  predicated  what  was  their  original  com- 
position as  a  whole. 

A.  E.  324,  from  Mitylene,  is  a  greenish-black  compact  rock  containing  lighter  green 
crystals  of  enstatite.  The  section  shows  a  grayish-brown  groundmass,  holding  crystals 
of  enstatite  and  diallage.  This  groundmass  is  formed  by  a  network  of  grayish-brown 
serpentine,  holding  olivine,  eustatite,  diallage,  and  iron  ore.  Much  of  the  enstatite  is 
altered  to  a  grayish-brown  fibrous  serpentine,  but  some  portions  remain  intact  in  part 
of  the  crystals,  while  other  crystals  are  entirely  unaffected.  The  diallage  is  abundant, 
but  in  small  irregular  grains  and  imperfect  crystals.  Part  of  this  appears  to  be  an 
augite-diallage,  for  it  has  well  developed  both  the  prismatic  cleavage  of  augite  and 
the  orthopinacoidal  cleavage  of  diallage,  as  well  as  traces  of  a  clinopinacoidal  cleavage. 
Elongated  dashes  of  iron  ore  are  occasionally  arranged  parallel  to  010,  forming  with 
the  well-developed  cleavage  parallel  to  100  a  rectangular  grating.  Part  of  the  iron 
ore  is  secondary,  occurring  in  grains  arranged  in  the  centre  of  the  serpentine  veins, 
but  part  appears  to  be  the  product  of  alteration  of  picotite,  since  the  interior  portion 
still  is  of  a  translucent  reddish-brown  color.  From  its  general  characters  the  ore  is 
probably  chromite  with  some  magnetite. 

A.  E.  208,  from  Qara-dagh,  is  of  a  similar  character,  but  has  less  enstatite  and  diallage, 
and  more  olivine.  In  some  places  the  olivine  has  suffered  almost  no  alteration,  while  in 
Others  the  change  is  complete.  The  rock  is  compact,  greenish-black,  containing  light- 
greenish  enstatite  crystals,  and  coated  with  a  greenish  "  slickenside  "  of  serpentine. 

A.  E.  209,  from  near  Mt.  Daydah  by  the  Plain  of  Troy,  is  a  grayish-green  rock  hold- 
ing enstatito  crystals  altered  into  a  talcose-like  material  (bastite)  and  presenting  a 
greenish  to  silvery-white  appearance.  The  section  is  similar  to  the  preceding,  but  more 
highly  altered,  the  serpentine  predominating.  The  diallage  is  abundant,  and  in  its 
structure  closely  resembles  that  of  the  meteorites,  being  composed  of  a  series  of  granules 
aggregated  together  into  larger  masses,  and  separated  by  little  patches  of  different 
material. 

A.  E.  481,  from  the  southeast  part  of  the  Chiplak,  Mt.  Ida,  is  a  dark-green  rock 
weathering  brown  and  containing  talc  scales  and  grains,  and  bands  of  chromite.  The 
section  is  grayish,  and  presents  a  schistose  appearance,  owing  to  the  arrangement  of 
its  iron  ore,  etc.  It  is  composed  principally  of  a  serpentine  network  enclosing  olivine. 
A  little  enstatite  and  diallage  were  observed,  also  iron  ore  and  secondary  talc. 

*  With  tliis  statement  of  Mr.  Diller  the  present  writer  is  unable  to  agree. 

19 


146  PERIDOTITE. 

A.  E.  207,  four  miles  northwest  of  Eanedeli,  is  a  compact  greenish-brown  rock,  weath- 
ering rusty-brown,  and  contains  enstatite  crystals.  Section :  greenish-gray  and  composed 
principally  of  secondary  serpentine,  with  its  network  structure  holding  later  altered  oli- 
vine  grains,  and  altered  enstatite  crystals  containing  much  iron  ore,  and  traversed  and 
stained  by  ferruginous  material.  Many  of  the  olivine  grains  between  the  meshes  appear 
in  common  light  as  unchanged  olivine,  but  in  polarized  light  the  change  to  serpentine  is 
seen  to  be  complete.  Some  dolomite  occurs,  while  portions  of  the  section  present  a 
similar  structure  to  that  given  in  figure  4,  Plate  VI. 

A.  E.  482,  from  the  central  part  of  the  Chiplak,  Mt.  Ida,  is  a  greenish-gray  schistose 
rock  closely  resembling  some  mica  schists  owing  to  its  contained  talc  scales.  It  holds 
actinolite  and  yellowish-brown  altered  olivine.  Section  •  greenish-gray  and  composed  of 
oliviiie,  iron  ore,  secondary  serpentine,  talc,  and  actinolite.  I  am  inclined  to  regard  this 
rock  as  an  altered  massive  rock,  instead  of  a  metamorphosed  sedimentary  one. 

A.  E.  265,  from  the  summit  of  Alt.  Ida,  is  a  similar  schistose  rock,  composed  of 
olivine  and  actinolite,  with  talc  scales  lying  between  the  lamination  planes.  The  section 
is  composed  partially  of  olivine,  which  is  somewhat  altered  to  a  dirty-green  serpen- 
tine, and  partially  of  actinolite  crystals.  Iron  ore  and  talc  also  occur.  Mr.  Diller 
has  called  this  a  talc  schist;  but  I  am  unable  to  agree  with  him,  for  it  appears  to 
me  to  be  a  metamorphosed  peridotite,  in  which  the  actinolite  and  talc  are  alteration- 
products.  The  foliation  appears  to  me  to  have  been  produced  during  the  metamorphosis, 
and  not  to  be  congenital. 

A.  E.  485,  from  the  northwest  summit  of  Mt.  Ida,  is  a  schistose  rock  of  a  grayish- 
green  color.  The  schistose  structure  appears  to  be  due  to  alteration  and  to  the  production 
of  talc  scales.  Section :  composed  of  a  network  of  greenish  serpentine  containing  olivine 
and  secondary  actinolite  and  talc.  The  form  of  the  olivine  grains,  and  their  relation  to  one 
another  and  to  the  other  minerals,  are  sucli  that  I  arn  unable  to  look  upon  them  as  either 
of  mechanical  or  of  metamorphic  origin.  The  actiuolite  is  clearly  an  alteration-product, 
and  frequently  separates  portions  of  the  same  olivine  -individual. 

There  are  two  rocks  numbered  A.  E.  483.  One,  coming  from  the  central  part  of  the 
Chiplak,  Mt.  Ida,  is  a  compact  greenish-black  rock  containing  talc  scales  and  weathered 
brown.  The  section  is  composed  of  serpentine,  olivine,  actinolite,  talc,  and  iron  ore. 
The  alteration  of  the  olivine  has  been  quite  extended  in  this.  The  second  A  E.  483  is 
from  the  northwest  summit  of  Mt.  Ida,  and  is  a  dark  compact  rock  with  little  trace  of  a 
schistose  structure.  The  section  is  composed  chiefly  of  serpentine,  talc,  iron  ore,  actino- 
lite, and  a  little  olivine. 

A.  E.  473,  from  the  summit  of  a  ridge  east  of  Mt.  Ida,  is  a  dark  greenish  and  grayish 
rock  weathering  brown.  It  is  a  surface  specimen.  Section  composed  of  a  network  of  green- 
ish serpentine  holding  olivine  grains,  and  associated  with  actinolite,  talc,  iron  ore,  etc. 

A.  E.  217,  from  the  Kemar  Valley,  is  a  compact  dark  grayish-green  rock  with  green- 
ish and  grayish  porphyritically  enclosed  enstatite  crystals.  The  section  is  composed 
principally  of  a  clear  pale  greenish  and  yellowish  serpentine,  holding  diallage,  enstatite, 
some  talc,  and  iron  ore.  The  serpentine  shows  traces  of  the  structure  of  the  minerals 
from  which  it  was  formed. 

A.  E.  216,  from  the  same  valley,  is  a  similar  rock,  and  in  the  hand  specimen  pre- 
sents considerable  resemblance  to  that  described  from  High  Bridge,  N.  J.  The  section 
is  much  like  that  of  A.  E.  217.  The  altered  enstatite  and  diallage  have  ferruginous 
material  so  arranged  in  their  fissures  as  to  give  them  a  close  resemblance  to  bronzite  and 
hyperstheue. 


THE  TI:I;I:I-:.STRIAL  PEUIDOTITES.  —  EULYSITE.  147 

A.  E.  214,  from  the  same  locality,  is  a  similar,  but  more  highly  altered  rock,  which 
contains  talc»si'  material 

The  greenish  talcose  schists  from  Mt.  Ida  are  stated  by  Mr.  Diiler  to  be  associated 
with  and  to  pass  into  the  oliviue-bearing  rocks  above  described  from  that  locality.  Ac- 
cepting the  accuracy  of  his  statement,  it  is  proper  to  touch  upon  their  microscopic  charac- 
ters so  far  as  they  bear  upon  this  relation. 

A.  E.  484  is  a  greenish  taleose  schist  containing  grains  and  crystals  of  magnetite. 
Stained  slightly  with  yellowish-brown  ferruginous  material  from  the  decomposition  of  the 
magnetite.  The  section  is  composed  principally  of  talc  holding  magnetite  and  patches 
of  partly  altered  olivine  and  enstatite,  traversed  by  a  peculiar  eozoon-like  network  of  iron 
ore,  with  the  longest  and  best  marked  portions  approximately  parallel  with  an  optic  axis. 

A,  E.  274  is  a  coarser  greenish-gray  talc  schist,  composed  of  talc  and  actinolite 
(Diller's  pyroxene)  with  iron  ore  and  the  remains  of  partially  altered  olivine. 

A.  E.  270  is  a  beautiful  green  talc  schist,  containing  crystals  of  actinolite  and  grains 
and  crystals  of  iron  ore.  Only  a  few  olivine  grains  were  seen. 

It  seems  to  me  from  the  study  of  these  rocks,  coupled  with  similar  evidence  obtained 
from  the  examination  of  other  rocks,  like  cumberlaudite,  that  these  schists  and  schistose 
forms  are  the  results  of  the  alteration  of  peridotites :  that  is,  the  schists  are  derived  from 
the  olivine  rock,  and  not  that  from  the  schists.  This  view  is,  of  course,  opposed  to  that 
of  Mr.  Diiler  and  the  majority  of  lithologists  and  geologists. 


VARIETY.  —  Eulysite. 

Tunalerff,  Norway. 

The  rock  from  which  this  variety  is  named  was  first  so  called  and  described  by  Axel 
Erdmann,  in  1849,  as  a  granular  mixture  of  diallage,  garnet,  and  altered  olivine.* 

According  to  the  later  studies  of  H.  von  Mold,  it  contains  fresh  clear  angular  grains 
of  olivine  cut  by  numerous  fissures  and  holding  much  magnetite  in  powdery  grains,  while 
the  olivine  is  here  and  there  altered  into  serpentine.  A  pale  sea-green  diallage  occurs, 
forming  large  grains  in  the  rock.  This  diallage  shows  a  fine  fibrous  parallel  structure 
(cleavage),  which  is  often  crumpled.  This  mineral  often  contains  layers  of  very  minute 
lamina,  which  make  with  the  cleavage  planes  angles  varying  from  20°  to  as  much  as  60° 
or  70°.  They  are  arranged  in  parallel  lines.  Pale  almandine-red  garnet  in  drop-like 
rounded  grains,  and  magnetite  also,  form  constituents  of  the  rock.  Mold  estimates  the 
percentages  of  the  minerals  as  olivine  (fayalite)  60  per  cent,  diallage  35  per  cent,  magne- 
tite 3  per  cent,  and  garnet  2  per  cent.f 

The  above  description  by  Mold  answers  very  well  for  the  section  in  this  collection 
purchased  from  Richard  Fuess.  The  general  structure  and  relations  of  the  crystals 
indicate  that  the  diallage  and  garnet,  if  not  all  of  the  minerals,  are  the  results  of  a 
recrystallization  of  the  rock  materials ;  i.  e.  it  appears  to  be  a  rock  whose  structure  has 
been  produced  by  alteration  and  secondary  crystallization,  with  but  little  if  any  of  the 
original  structure  and  minerals  remaining. 

Kettikfjdll,  Sweden. 

According  to  Tb'rnebohm,  this  rock  is  a  fine  granular  one,  greenish  on  the  fresh 
fracture,  ami  \\vathering  yellowish.  Microscopically  it  is  composed  of  irregular  olivine 

»  Ncues  Jalir.  Min,  1819,  pp.  837,  838.  f  Njt  Mag.,  1877,  xxiii.  119. 


148  PERIDOT1TE. 

grains,  colorless  pyroxene  (diopside),  colorless  mica,  and  chromite.  The  olivine  is  fresh, 
and  with  the  pyroxene  is  almost  free  from  inclusions.  The  chromite  is  brownish  on  the 
edges,  and  is  often  surrounded  or  accompanied  by  the  mica.* 

This  rock  is  said  to  be  associated  with  schists,  and  to  be  a  concordant  part  of 
them. 

Varallo,  Sesia  Valley. 

Prof.  A.  Stelzner  described  a  fine-grained  greenish-black  rock  from  Varallo,  in  Sesia 
Valley,  as  composed  of  olivine,  hornblende,  and  bronzite  in  nearly  equal  amounts.  Green 
grains  were  observed  which  were  isotropic  and  regarded  as  probably  chlorospinel.  f 

Lepce,  Austria. 

A  blackish  fine-grained  olivine  mass  with  light  greenish-gray  foliated  diallage  having 
a  metallic  lustre. 

The  section  is  composed  of  predominating  somewhat  serpentinized  olivine,  whose 
fissures  are  filled  with  a  black  powder ;  as  well  as  a  light  reddish-colored  diallage,  which 
is  fibrous  and  shows  a  feeble  dichroisra  between  light  red  and  light  green4 

Fonianapass,  Locris,  Greece. 

According  to  Becke  the  rock  from  this  locality  is  a  light-colored  fresh  olivinfels, 
holding  porphyritic  crystals  of  diallage. 

In  the  thin  section  it  is  seen  to  contain  the  following  minerals :  olivine  in  irregular 
colorless  fresh  grains,  traversed  by  numerous  irregular  fissures ;  serpentine  in  thin  plates 
along  these  fissures ;  diallage,  very  fresh,  and  traversed  by  cleavage  planes,  but  sometimes 
this  mineral  is  changed  to  a  rhombic  fibrous  alteration-product ;  and  picotite,  in  little 
reddish-brown,  translucent  quadratic  or  hexagonal  sections. 

A  somewhat  similar  rock  comes  from  Pyrgos,  at  the  foot  of  Hymettus,  in  Attica. 
This  has  a  black  and  green  spotted  groundmass  holding  large  crystals  of  enstatite  which 
are  much  altered  (bastite). 

In  the  section  the  rock  shows  the  ordinary  network  of  serpentine,  to  which  the 
olivine  has  been  entirely  changed.  Picotite  and  magnetite  occur.§ 

Mohsdorf,  Saxony. 

This  rock,  Dathe  states,  contains  as  its  most  prominent  mineral  diallage.  Sometimes 
along  the  fissures  are  alteration-products  of  calcic  carbonate  and  iron.  The  olivine 
which  is  held  by  the  diallage  is  generally  altered  to  serpentine,  which  is  filled  with  a 
powder  of  iron  ore.  Some  garnet  occurs.  || 

Gillsberg,  Saxony. 

According  to  Dathe,  this  is  a  dark  green  rock  composed  of  dark  brown  to  black 
elongated  crystals,  which  in  the  thin  section  are  dichroic  from  light  brown  to  dark  brown, 

*  Geol.  Foren.  Forh.,  1877,  iii.  250;  Neues  Jahr.  Min.,  1880,  ii.  197. 
f  Zeit.  Deut.  geol.  Gesell.,  1876,  xxviii.  623-625. 
t  C.  v.  John,  Jahr.  Geol.  Reichs.,  1SSO,  xxx.  447. 
§  Min.  MiUh.,  1878  (1),  i.  475-477. 
||  Neues  Jahr.  Min.,  1876,  pp.  233. 


THE   TERRESTRIAL   PERIDOTITES.  —  PICRITE.  149 

and  have  the  cleavage  of  hornblende,  garnet,  olivine  altered  to  serpentine  in  part,  biotite 
strongly  dichroic  and  containing  little  opaque  needles,  diallage,  and  iron  ore.* 

A  similar  serpentine   was  described   by   Bathe  from   Crossen,  near  Mittweida,  iu 
Saxony ;  but  it  appears  to  be  a  somewhat  more  altered  rock  (I.  c.,  p.  245). 


VARIETY.  —  Picrite. 

Austria. 

Picrite,  according  to  Tscherrnak,  when  in  a  fresh  or  little  changed  state,  has  a  dark 
green  color,  and  varies  from  a  finely  crystalline  to  a  plainly  crystalline  character. 

That  from  Sohle  has  a  blackish  groundmass  containing  a  large  number  of  olivine 
crystals.  Microscopically  the  groundmass  holds  granular  feldspar,  grains  of  magnetite, 
scales  of  black  mica,  and  little  hornblende  crystals. 

The  Freiberg  and  Gumbelberg  picrite  shows  a  dark  groundmass  holding  olivine 
crystals  traversed  by  numerous  fissures  filled  by  a  serpentinous  mineral ;  also  blackish- 
green  grains  of  diallage.  The  groundmass  is  similar  to  that  of  the  Sohle  picrite :  granu- 
lar feldspar,  biotite  scales,  magnetite  grains,  and  a  few  hornblende  crystals,  with  here  and 
there  thin  strings  of  serpentine. 

The  picrite  from  ScMnau  has  a  blackish-green  groundmass  holding  olivine  and  dark- 
green  mica.  The  mica  forms  aggregations  of  scales.  Much  serpentine  also  occurs  in  the 
rock.  The  groundmass  consists  of  a  granular  feldspathic  mass,  grains  and  octahedrons 
of  magnetite,  blackish-green  augite  crystals,  rarely  some  needles  of  apatite,  also  calcite 
grains,  and  some  serpentine. 

An  altered  picrite  from  SoMe  is  a  dark  greenish-gray  rock  flecked  with  pistacite 
green  spots.  It  contains  altered  diallage  and  olivine  crystals,  hornblende  prisms,  dark- 
green  mica  plates,  magnetite  grains,  and  silicates  like  gymnite  and  palagonite.  . 

Another  altered  picrite  from  Bystryc,  has  a  clear  gray  very  fine-grained  groundmass, 
holding  inclusions  of  bluish-gray  to  apple-green  and  blackish-green  colors.  Pseudo- 
morphs  after  diallage  and  olivine  occur,  while  the  rock  further  contains  magnetite  and 
fine  fissures  filled  with  calcite. 

The  above  picrites  are  stated  to  be  eruptive  in  the  Cretaceous. 

Steierdorf,  Banat. 

A  blackish  rock  resembling  basalt,  and  containing  porphyritically  enclosed  olivine  and 
quartz.  It  is  somewhat  porous,  and  holds  calcite  amygdules.  The  section  shows  that 
the  principal  minerals  are  olivine,  augite,  and  hornblende.  Calcite  occurs  as  an  alteration- 
product,  and  quartz  as  an  inclusion,  while  an  isotropic  base  was  seen.  The  olivine  is  in 
large,  well-defined  crystals,  and  in  smaller  rounded  forms.  It  is  for  the  most  part  fresh, 
but  it  shows  here  and  there  along  its  edges  and  the  borders  of  its  fissures  an  alteration  to 
a  dark  brown  radiated  fibrous  aggregate.  The  olivine  contains  inclusions  of  glass,  augite, 
hornblende,  and  picotite.  The  latter  is  in  large  brown  isotropic  sharply  defined  octahe- 
drons. The  augite  is  of  a  light-reddish  color,  and  the  crystals  are  fresh  with  a  feeble 
pleochroism.  It  contains  inclusions  of  glass  and  picotite.  The  hornblende  is  of  a  dark 
brown  color,  with  strong  pleochroism,  and  contains  glass  particles.  The  hornblende  is 

»  Neues  Jalir.  Min.,  1876,  pp.  241,  245. 


150  PERIDOTITE. 

often  associated  with  the  augite.     The  quartz  is  in  water-clear,  beautifully  polarizing  fis- 
sured grains  containing  fluid  and  glass  inclusions,  as  well  as  apatite  needles.* 

Inclicolm  Island,  Scotland. 

An  apparent  intrusive  mass  is  described  by  Dr.  A.  Geikie  as  composed  of  a  serpenti- 
iious  base  holding  honey-yellow  grains  of  olivine,  dark  lustrous  augites,  and  a  few  plates 
of  brown  biotite.  In  the  section  the  olivine  is  in  a  great  measure  undecomposed,  though 
presenting  the  usual  exterior  band  and  transverse  threads  of  serpentine.  The  augite  is 
of  a  pale  yellow  color,  and  in  large  and  well-defined  prisms,  often  enclosing  olivine.  A 
little  milky  plagioclase  full  of  fissures  and  decomposition  products  was  observed.  Long 
scales  of  rich  brown  biotite  occur  here  and  there  ;  also  a  few  plates  and  grains  of  probable 
titaniferous  iron.  One  of  the  most  conspicuous  constituents  is  a  rich  emerald-green  to 
grass-green  decomposition  product,  filling  up  the  interstices  and  running  in  veins  and 
irregular  streaks  or  tufts  through  the  rock.  Other  pale  or  colorless  aggregates,  which  are 
sometimes  distinctly  fibrous,  also  occur.  These  various  decomposition  products  some- 
times show  the  polarization  of  serpentine,  and  sometimes  that  of  chlorite.  Some  zeolitic 
fibrous  tufts  were  seen.f 

Herborn,  Nassau. 

The  section  purchased  from  Eichard  Fuess  is  composed  of  pale  brownish-yellow  augite 
and  clear  fissured  olivine  surrounded  and  held  by  the  secondary  serpeutinous  products. 
The  augite  in  places  is  changed  to  a  pleochroic  green  fibrous  mineral,  whose  extinction, 
being  parallel  to  the  nicol  diagonal,  presents  a  strong  contrast  in  polarized  light  to  the  mono- 
clinic  augite.  The  augite  holds  numerous  rounded  grains  of  olivine,  the  same  as  enstatite 
commonly  does  in  other  rocks.  The  olivine  is  in  rounded  fissured  forms,  surrounded  and 
traversed  by  the  plexus  of  alteration  material.  Part  of  the  latter  is  dichroic,  varying  from 
a  green  to  brownish-yellow,  and  from  its  relations  to  the  secondary  brownish-yellow  biotite 
it  is  regarded  as  a  transition  stage  in  the  formation  of  the  biotite.  It  is  in  irregular  fibrous 
forms,  the  fibres  being  crumpled  and  aggregated  together.  In  other  portions  some  whitish 
fibrous  material  occurs,  which  affects  polarized  light  in  the  same  manner  as  part  of  the  ac- 
tinolite  does  in  the  cunibcrlandite.  However,  the  chief  portion  of  the  alteration  material 
is  serpentine.  The  olivine  is  in  part  very  clear,  and  in  part  changed  to  a  pale-yellowish 
serpentine  filled  with  globulites  and  margarites  of  iron  ore.  They  are  seen  in  the  serpen- 
tine veins  ramifying  through  the  olivine,  and  projecting  like  pseudopodia  from  the  sur- 
rounding material  into  the  partially  or  entirely  altered  olivine.  The  ore  also  forms 
black  grains  and  crystals  (some  of  which  are  octahedrons)  in  the  olivine,  and  in  the 
network  of  alteration  material.  It  frequently  forms  black  bands,  rows  of  grains,  or  fine 
powder,  along  the  fissures  or  centres  and  sides  of  the  serpentine  veins.  The  biotite 
is  in  irregular  yellowish-brown  scales  and  grains,  some  of  which  are  surrounded  by  the 
black  ore  grains.  It  is  strongly  dichroic,  and  shows  oftentimes  a  wavy,  fibrous  polar- 
ization. (Plate  VIII.  figure  6.) 

Ellc/olh,  Austria. 

This  rock  is  described  by  Dr.  H.  v.  Mb'hl  as  having  a  black  to  blackish-green  serpen- 
tinous  groundmass  holding  many  mica  and  hornblende  particles. 

The  section  is  in  part  a  very  fine  tufted  serpentine,  and  in  part  a  scaly  fibrous  one,  of 

*  E.  Hussak,  Verhandl.  Gcol.  Rciolis.,  1881,  pp.  258-262. 
t  Trans.  Roy.  Soc.  Ediu.,  18/9,  xsix.  506-508. 


THE  TERRESTRIAL   PERIDOTITES.  —  PICRITE.  151 

all  possible  colors  from  a  pale  apple-green  to  a  brilliant  grass-green,  bright  ochre-yellow, 
siskin-green,  and  reddish-brown,  one  color  running  into  the  others.  Further,  there  occur 
ivninants  of  the  olivine  grains  having  a  light  or  ochre-yellow  tinge,  and  also  magnetite 
and  gothite.  The  olivine  remnants  when  untouched  by  alteration  are  colorless,  very 
pellucid,  beautifully  polarizing,  but  extraordinarily  rich  in  fissures,  whose  edges  are  cloudy 
with  minute  magnetite  grains.  Some  show  a  light  blue  color,  owing  to  exceedingly 
minute  powder-like  grains.  Vapor,  glass,  and  fluid  cavities,  as  well  as  spinel  inclusions, 
occur  sparingly. 

The  serpentine  mass  includes  fiery  reddish-brown  mica ;  very  light  grayish-brown, 
finely  fibrous,  or  step-like,  rough,  feebly  dichroic  enstatite ;  a  little  clear  light-brown, 
fir  lily  dichroic  augite,  traversed  by  irregular  fissures;  and  strongly  dichroic  fissured  horn- 
blende, varying  from  clear  ochre-yellow  to  a  deep  blackish-brown.  A  little  apatite  and 
plagioclase  were  also  observed.  This  is  a  cretaceous  or  tertiary  eruptive  rock.* 

Pen-y-carnisiog,  Anglesey. 

According  to  Bonney  this  rock  in  the  section  is  seen  to  be  composed  of  augite,  horn- 
blende, actinolite,  magnetite,  opacite,  serpentinous  material,  etc. 

Augite  occurs  in  colorless  grains  and  crystals,  some  of  which  show  a  characteristic 
cleavage.  The  hornblende,  including  actinolito,  is  in  (1st)  innumerable  small  acicular  or 
blade-like  crystals,  in  irregular  tufted  groups,  which  are  pale  greenish  or  colorless,  and 
feebly,  if  at  all,  dichroic ;  (2d)  small  crystals  often  exhibiting  characteristic  cleavages  and 
even  crystallographic  planes,  green-colored  and  strongly  dichroic ;  and  large  brown  crys- 
tals, supposed  to  be  pseudomorphs  after  augite.  These  minerals  occur  in  a  serpentinous 
or  chloritic  grouudmass  containing  no  unchanged  olivines,  but  pseudomorphs  after  that 
mineral  were  thought  to  be  observed.  Some  talc  (?)  was  seen,  as  well  as  other  micaceous 
secondary  products.^ 

Later  Professor  Bonney  found  a  number  of  boulders  of  this  rock  on  the  western  coast 
of  Anglesey.  In  general  these  were  similar  to  the  one  just  described,  although  in  one 
some  decomposed  feldspar  and  some  diallage  were  observed.  A  little  apatite,  mica,  etc. 
were  seen  in  some  of  the  sections.J 

Near  the  River  Dill  ("  Dillgcgcnd"},  Nassau. 

This  rock  in  the  fresh  condition  has  a  blackish-green  color,  and  contains  copper-col- 
ored mica,  green  chromdiopside,  hypersthene,  picotite,  and  magnetite. 

The  oliviue  is  in  water-clear  to  pale  yellowish-green  grains,  traversed  by  fissures 
along  which  occurs  a  fibrous  greenish  or  yellowish-green  serpentine  containing  mag- 
netite grains,  etc.  The  chromdiopside  appears  as  a  rule  in  irregvdar  leek-green  grains 
showing  cleavage,  and  is  sometimes  altered  to  a  leek  or  smaragdite-green  serpentinous 
aggregate. 

The  hypersthene  is  pale-brownish,  and  shows  an  evident  brachypinicoidal  cleavage. 
It  contains  the  usual  violet-brown  lamina?,  and  olivine  grains. 

The  mica  shows  a  reddish-brown  color  darker  than  the  hypersthene,  is  dichroic,  and 
H"<K;iatcd  with  the  magnetite.  The  picotite  is  in  deep  black  octahedral  crystals,  which 
are  dark  brown,  and  feebly  translucent  on  the  thin  edges. 

•  Ncucs  Jahr.  Min.,  1875,  pp.  700-7"3.  f  Quart.  Jour.  Geol.  Soc.,  1881,  xxxvii.  137-110. 

J  Quart.  Jour.  Geol.  Soc.,  1883,  xxxix.  254-260. 


152  PERIDOTITE. 

Beside  the  magnetite,  there  occurs  a  whitish  opaque  mineral  substance,  which  is  con- 
sidered to  be  magnesite. 

A  similar  rock,  which  comes  from  the  nickel  mine  Hulfe  Gottes  in  the  Weyherhecke, 
Nassau,  is  described  as  a  granular  to  compact  serpentine  of  a  dark-green  color.  In  the 
dark  groundmass  lie  many  minerals;  as,  for  instance,  calcite,  magnesite,  chrysotile,  schiller- 
spar,  pyrite,  chalcopyrite,  and  millerite.  The  olivine  is  mucli  changed  to  serpentine,  as 
also  is  the  hypersthene.  The  chief  difference  between  this  and  the  preceding  appears 
to  be  mainly  in  the  greater  amount  of  alteration.* 


VARIETY.  —  Serpentine. 

Fitstown,  Berks  Co.,  Pennsylvania. 

1562.  Section :  a  greenish-yellow  serpentine  holding  crystals  of  grayish-white  dolo- 
mite. Under  the  microscope  in  part  of  the  section  the  serpentine  is  seen  to  form  a  net- 
work following  the  fissures  in  the  clear,  unaltered  olivine,  and  enclosing  grains  of  it,  the 
fibres  being  generally  parallel  to  the  direction  of  the  serpentine  veins.  In  other  portions 
only  traces  of  the  olivine  remain,  while  in  still  others  only  the  structure  of  the  serpentine 
shows  its  origin.  The  direct  conversion  of  olivine  into  serpentine  is  well  illustrated  in 
this  section.  The  dolomite  is  in  rhombohedrons,  and  irregular,  sometimes  geuiculated 
grains.  The  larger  forms  mostly  contain  an  irregular  central  portion  of  a  clear,  fissured 
mineral,  closely  resembling  olivine  in  its  clearness ;  but  it  is  isotropic,  and  belongs  to 
spinel.  One  grain,  however,  showed  a  pale  grayish  color  in  polarized  light.  The  dolo- 
mite is  surrounded  by  a  white  border  of  aggregately  polarizing  fibrous  serpentine,  which 
in  places  occupies  considerable  of  the  section.  The  serpentine  about  the  olivine  is  in 
the  middle  of  the  fissures  of  a  clear  greenish-yellow  color,  but  next  the  olivine  frequently 
passes  into  a  clear  nearly  white  serpentine.  (Plate  VII.  figure  6.) 

The  rock  is  composed  of  a  mixture  of  greenish  and  yellowish  serpentine  and  grayish- 
white  dolomite.  Many  colorless  and  pale  bluish  octahedrons  of  spinel  were  observed  in 
the  dolomite.  Three  of  the  sides  of  the  specimen  show  a  "  slickensided  "  surface  coated 
with  serpentine,  dolomite,  and  white  mica  (phlogopite  ?).  This  rock  is  an  "  ophicalcite." 

Frankenstein,  Silesia. 

Prof.  T.  Liebisch  describes  this  rock  as  a  siskin-green  to  oil-green  serpentine  mass 
holding  chromite.  In  the  section  it  shows  the  usual  network  of  serpentine  enclosing 
colorless  oliviue  grains,  minute  crystals  of  actinolite,  and  whitish  talc-like  plates,  f 

LeJi'd,  Nonvay. 

The  section  shows  portions  in  which  the  olivine  is  still  unaltered,  but  it  is  rendered 
cloudy  by  a  magnetite  dust  scattered  througli  it. 

In  other  portions  the  magnetite  is  very  abundant,  and  in  polarized  light  the  rock  is 
seen  to  contain  numerous  plates  and  fibres,  having  a  similarity  to  sericite,  or  to  talc  and 
chlorite.  It  contains  grains  of  a  magnesium  carbonate.  $ 

»  Konrad  Oebbeke,  Inaug.  Diss.,  Wurzburg,  1877,  38  pp. 

f  Zeit.  Deut.  geol.  Gescll.,  1877,  xxix.  732.  }  Mohl,  Nyt  Mag.,  1877,  xxiii.  121. 


THE  TERRESTRIAL   PERIDOTITES.  —  SERPENTINE.  153 


,  Saxony. 

5002.  A  dark  grayish-green  rock,  purchased  from  Voigt  and  Hochgesang,  mottled 
with  spots  of  lighter  grayish-green,  and  containing  chromite. 

Section  :  greenish-gray  with  a  reticulated  network  of  iron  ore.  Chiefly  composed  of 
clear  colorless  or  pale  yellow  and  pale  green  serpentine.  This  retains  in  part  the  structure 
of  the  fissured  olivine,  and  in  part  that  of  the  enstatite  crystals  which  it  has  replaced. 
In  the  latter,  the  plane  of  extinction  is  the  same  as  that  of  the  enstatite,  while  in  the 
serpentine  replacing  the  olivine  we  have  the  reticulated  network  following  the  fissures, 
with  the  polarization  of  the  serpentine  first  formed  along  the  fissures  differing  from  that 
later  replacing  the  central  portions  of  the  grains.  This  difference  is  to  some  extent 
observable  in  common  light,  so  that  one  is  able  to  trace  out  the  forms  of  the  original  en- 
statites,  and  then  those  of  the  olivine  grains  which  were  enclosed  in  them.  The  structure 
of  the  rock  thus  revealed  shows  that  it  was  originally  composed  principally  of  olivine 
with  comparatively  small  amounts  of  enstatite. 

The  "Wsildlii'iiii  serpentines  have  been  studied  by  Dathe,  who  describes  that  from  the 
Tunnel  as  a  blackish-green  stone  holding  small  garnets  and  many  clear  vitreous  points. 
The  section  is  composed  of  well-marked  olivine  grains,  with  the  secondary  serpentine, 
magnetite,  garnet,  picotite  or  chromite,  and  diallage.  That  from  the  Quarry  on  the  Gebcrs- 
bach  is  a  dark-green  serpentine  showing  olivine  grains.  In  the  section  the  olivine  shows 
various  degrees  of  alteration  to  an  ore-bearing  serpentine,  forming  the  usual  reticulated 
network.  It  also  contains  diallage  and  garnet,  the  latter  of  which  is  sometimes  altered 
into  chlorite.  The  serpentine  from  the  Breitenberg  is  of  two  kinds:  one  a  dark  green 
serpentine,  hard  and  brittle,  and  carrying  garnet,  and  the  other  softer,  tougher,  and 
wanting  garnets.  The  former  answers  in  character  to  the  Tunnel  and  Quarry  serpen- 
tines, while  the  latter  shows  the  network  structure  of  serpentine,  and  holds  iron  ore  and 
enstatite  (bastite).* 

Kokkino-Nero,  TJmsaly. 

Dark,  nearly  black  compact  rock,  traversed  by  strings  of  yellowish-green  fibrous  ser- 
pentine. In  the  section  it  shows  the  usual  network  of  serpentine  associated  with  altered 
diallage  or  enstatite  crystals. 

Similar  to  this  is  a  rock  from  Polydendri  which  contains  both  altered  diallage  and 
enstatite,  as  well  as  garnet  and  picotite  grains. 

A  similar  rock  from  Neokhori  shows  comparatively  fresh  diallage  traversed  by  fine 
parallel  fissures  along  which  are  arranged  small  needles  and  plates,  f 

Between  the  Rivers  Dajao  and  Cenobi,  Province  of  Santiago,  San  Domingo. 

120  G.  A  dark-brown  rock  flecked  with  greenish  spots.  Contains  a  little  talc,  and 
is  traversed  by  serpentine  veins  having  greenish  borders  and  a  dark  central  line  owing 
to  the  iron  ore  in  it.  (W.  M.  Gabb,  Collector.) 

Section  :  banded  greenish-yellow  and  black.  The  greenish-yellow  portions  are  seen  to 
be  composed  of  yellowish  pseudomorphs  of  serpentine  after  olivine,  traversed  by  fissures 
and  surrounded  by  a  network  of  whitish  fibrous  serpentine  with  the  fibres  arranged  per- 
pendicular to  the  course  of  the  veinlets.  In  other  portions  the  remains  of  some  apparent 
pyroxunic  mineral  occurs,  while  elsewhere  the  serpentinous  material  is  quite  compact,  but 

«  Ncues  Jahr.  Min.,  1876,  pp.  239-243.  f  Becke,  Min.  Mittb.,  1S78  (1),  i.  472,  473. 

20 


154  PEEIDOTITE. 

shows  to  some  extent  the  characters  of  serpentine  replacing  olivine.  The  dark  band  is 
formed  of  irregular  masses  and  grains  of  iron  ore,  arranged  in  the  serpentine  in  a  vein-like 
form.  Some  of  the  serpentinous  material  is  isotropic.  The  structure  of  a  portion  of  the 
section  is  shown  in  figure  1,  Plate  VI. 

At  the  foot  of  the  first  rise  on  the  ridge,  edge  of  the  river  on  the  road  from  La  Vega 
to  Jarabacoa,  Province  of  La  Vega,  San  Domingo. 

142  G.  A  dark  reddish-brown  compact  rock,  breaking  with  a  conchoidal  fracture. 
Traversed  by  some  veins  of  a  greenish-white  serpentine.  Contains  many  bronze-like 
crystals  of  altered  enstatite  (?).  ( W.  M.  Gabb,  Collector.) 

Section :  a  brownish  and  greenish  mass  composed  of  serpentine,  dolomite,  picotite  or 
chromite,  and  ferrite  products.  The  usual  arrangement  of  the  serpentine,  in  a  network 
following  the  outlines  and  fissures  of  the  original  olivine  grains,  is  seen ;  this  is  marked 
by  veins  formed  by  brown  and  black  dust  and  grains  of  ferruginous  material  mixed  witli 
serpentines,  having  a  similar  arrangement  to  that  observed  in  the  California  peridotites. 
Bordering  these  veins  is  a  band  of  whitish  serpentine,  which  sometimes  occupies  the 
entire  interspace.  In  the  majority  of  cases  the  portions  between  the  veinlets  are  com- 
posed of  a  greenish-yellow  serpentine  having  the  form  and  outline  of  the  fractured 
olivine  grains. 

Lying  in  the  sections  are  a  number  of  white,  greenish,  and  grayish  patches,  of  the  same 
outline  as  the  pyroxene  minerals  usually  occurring  in  the  peridotites.  They  enclose 
rounded  portions  of  the  serpeutinized  olivine  ;  and  in  part  have  the  fibrous  cleavage  of 
enstatite,  while  in  part  their  structure  is  irregular.  They  show  aggregate  and  fibrous 
polarization  as  a  rule,  but  occasionally  the  optical  characters  of  altered  enstatite.  Pico- 
tite or  chromite  occurs  in  irregular  masses  of  a  black  and  translucent  deep  coffee-brown 
color.  Its  grains  are  traversed  by  fissures  and  black  bands,  part  of  which,  in  reflected 
light,  show  metallic  lustre  with  numerous  crystalline  facets. 

Some  dolomite  with  well-marked  cleavage  occupies  a  portion  of  one  section,  in  the 
form  of  irregular  somewhat  rounded-  patches.  A  few  veins  traverse  the  mass,  having  been 
formed  after  the  main  serpentinous  alteration  of  the  rock.  The  whole  section  is  sprinkled 
with  black-brown  and  yellowish-brown  grains,  dust,  and  aggregations  of  ferruginous 
material.  The  structure  of  this  rock  is  shown  in  Plate  V.  figure  4. 

Brixlegg,  Tyrol. 

According  to  Von  Drasche  this  shows  a  compact  network  of  magnetic  iron  grains,  with 
a  fibrous  serpentine  mass,  which  encloses  some  remaining  grains  of  olivine  and  diallage. 
The  serpentine  is  said  beyond  question  to  have  resulted  from  the  alteration  of  olivine  and 
diallage.* 

11  Piano,  Elba. 

A  greenish-brown  mass  traversed  by  talcose  (?)  veins,  and  containing  altered  enstatite 
crystals. 

Under  the  microscope  it  is  seen  to  be  composed  of  brownish,  greenish,  and  yellowish 
serpentine  largely  filled  with  black  dust-like  granules,  having  a  network  structure  and 

*  Min.  Mitth.,  1871,  i.  2.  Sec  also  E.  Hussak,  Ibid.,  1882  (2),  v.  76,  77,  who  found  augite  in  this 
rock,  and  throws  some  doubt  on  the  correctness  of  Drasehe's  work. 


THE   TERRESTRIAL   TERIDOTITES.  —  SERPENTINE.  155 

cut  by  talcose  (?)  veins  which  are  crossed  by  later  chrysotile  ones.  The  enstatite  is 
in  part  altered  to  the  talc-like  material,  and  in  part  to  serpentine.  It  is  probable  that 
olivine  predominated  over  the  eustatite  when  the  rock  was  unaltered.  This  was  pur- 
chased from  Voigt  and  Hochgesang. 

Launceston,  Tasmania. 

* 

5170.  A  dark  green  rock,  purchased  of  Ward  and  Howell,  sprinkled  with  chromite 
and  talc  scales.  Weathers  greenish-white. 

Seetion:  greenish-gray  with  cloudy  blotches.  Composed  of  a  pale  yellowish  fibrous 
serpentine  showing  brilliant  polarization,  and  altered  enstatite  crystals,  talc  scales,  and 
chroinite.  The  talc  is  grayish-white,  of  feeble  polarization,  and  usually  associated  with 
the  iron  ore.  In  some  cases  it  is  dichroic,  varying  from  a  gray  or  yellowish-gray  to  a 
pale  bluish  tint.  The  enstatite  in  some  cases  retains  its  original  plane  of  extinction, 
although  altered  to  a  pale  yellowish  serpentine  mass.  The  cloudy  spots  are  caused  by 
innumerable  grains  of  iron  ore  locally  concentrated. 

Windisch-Matrey,  Tyrol. 

According  to  Von  Drasche  this  serpentine  is  interbedded  in  a  calcareous  mica  schist. 
The  color  varies  from  a  light  green  to  a  deep  green  or  brown,  and  the  rock  is  sprinkled 
with  calcite,  asbestos,  and  chrysotile  grains  and  fibres.  Drasche  placed  the  specimens  in 
two  divisions. 

1.  This  is   an  olive-green  rock   flecked   with  yellowish-brown   spots,   and  contains 
diallage,  ankerite,  and  a  white  scaly  mineral  with  irregular  outlines.     The  section  under 
the   microscope  shows   a  groundmass   formed  from  a   compact   network   of  a  rhombic 
mineral,  which  occupies   the   principal  portion  of  the  section.      In  addition   grains   of 
magnetite  and  diallage  were  seen.     Some  talc  was  also  observed. 

2.  The  other  variety  is  a  dark-green  very  fine-grained  rock  sprinkled  with  light-green 
diallage  crystals  and  white  talc  plates.     The  section  under  the  microscope  is  seen  to 
contain  the  network   formed   by  the   rhombic  mineral,  magnetite  arranged   in  bands, 
diallage,  etc.* 

The  section  in  the  Whitney  collection  from  Voigt  and  Hochgesang,  from  this  locality, 
has  the  following  characters.  Color  pale  green,  but  broken  by  veins  and  spots  of  black 
in  in  ore.  In  polarized  light  the  section  shows  the  usual  structure  of  a  serpentinous  rock 
produced  by  the  alteration  of  a  peridotic  one.  It  contains  scales  of  talc  and  granular 
masses  of  pyrite.  Some  of  the  iron  ore  is  in  forms  resembling  the  picotite  grains  in  the 
Like  Lherz  rock.  These  forms  are  traversed  by  fissures,  and  in  reflected  light  it  is  seen 
that  the  ore  bordering  them  is  crystalline  showing  metallic  lustre,  while  the  remaining 
portions  do  not  present  these  characters.  The  talc  is  so  arranged  that  it  appears  to  have 
arisen  from  the  conversion  of  enstatite  material.  The  rock  apparently  contained  originally 
oliviue,  enstatite,  and  picotite  at  least.  The  section  is  traversed  by  veins  of  serpentine 
and  talcose  material. 

St.  Saline,  Vosges,  France. 

5169.     .V  greenish-black  compact  rock,  weathering  grayish-brown. 
Section  :    pale  green,  and  composed  of  serpentine  in  which  a   few  altered  enstatite 
grains  were  observed.     A  few  nodules  occur  which  are  formed  in  the  interior  of  grayish 

»  Min.  Mini..,  1871,  i.  3-8.    See  also  E.  Hussak,  Ibid.,  18S2  (2),  v.  78-80. 


156  PERIDOTITE. 

fibrous  material  having  a  feeble  polarization  and  containing  irregular  brownish-yellow 
spots,  which  affect  polarized  light  more  than  the  enclosing  material  does.  The  exterior 
portion  of  these  nodules  is  formed  of  pyroxene  granules  (diallage)  somewhat  serpentinized 
with  irregular  grains  of  a  deep-green  color  and  isotropic,  —  pleonaste. 

River  Oisain,  Timor. 

Dr.  A.  Wichmann  describes  from  the  Eiver  Oisain  a  serpentine  of  a  dark  bluish-gray 
color,  porphyritically  holding  bronzite  crystals  and  small  grains  of  calcite. 

Microscopically  the  serpentine  has  the  usual  mesh  structure,  and  contains  within  its 
interstices  colorless  patches  showing  aggregate  polarization.  Opaque  grains  of  iron  ore 
are  common.  The  bronzite  is  altered,  and  contains  along  the  cleavage  lines  a  blackish- 
brown  aggregate  of  minute  plates  as  well  as  black  needles.  Chromite  in  brown  trans- 
lucent grains,  and  calcite  also,  were  seen.* 

Range  11,  Riviere  des  Plantes,  Canada. 

According  to  Mr.  Frank  D.  Adams,  this  serpentine  contains  a  few  remains  of  a 
rhombic  pyroxene  (enstatite),  which  are  slightly  pleochroic  and  have  numerous  black 
needles  arranged  parallel  to  the  cleavage  and  rhombic 


Melbourne,  Canada. 

According  to  the  preceding  observer,  this  rock  is  of  a  dark-green  color,  and  composed 
of  a  serpentine  mass  containing  some  irregular  fragments  of  a  rhombic  pyroxene  (en- 
statite). These  show  pleochroisrn  varying  from  green  to  a  reddish  color,  and  have  a 
well-marked  cleavage  or  fibrous  structure.'f 

Galicia,  Spain. 

The  serpentines  of  this  country  are  composed,  according  to  Macpherson,  principally  of 
serpentine  produced  from  the  alteration  of  olivine,  and  holding  the  remains  of  enstatite  or 
diallage  crystals,  etc.J 

High  Bridge,  Hunterdon  Co.,  New  Jersey. 

1403.  A  mottled  rock  of  black  and  oil-green,  having  a  reticulated  and  somewhat 
banded  structure.  The  powder  of  the  rock  is  attracted  by  the  magnet,  and  tests  show 
the  presence  of  chromium. 

Section  :  greenish-white  with  black  and  dirty-brown  spots.  The  least  altered  portions 
are  the  dark  spots,  with  their  included  crystal  forms.  The  spots  show  the  structure  in 
common  and  polarized  light  of  serpentinized  olivine,  while  the  crystal  forms  present  a 
cleavage  similar  to  that  of  some  enstatite,  but  more  like  that  of  diallage.  Both  spots  and 
crystals  are  now  completely  changed  to  serpentinous  material.  The  main  mass  of  the 
section  is  white,  slightly  tinged  in  places  with  a  pale  yellowish-green  color.  It  is 
traversed  by  fissures,  and  contains  much  disseminated  iron  ore  in  dust,  grains,  and  irreg- 
ular aggregations.  In  common  light  this  groundmass  shows  but  little  evidence  of  its 
origin,  but  in  polarized  light  there  is  distinctly  revealed  the  usual  network  of  serpentine 
fibres  when  formed  from  the  alteration  of  an  olivine  rock.  The  story  of  the  change  can 

*  Samml.  Geol.  Mus.  Leiden,  1884,  ii.  105-110.  J  Anal.  Soc.  Esp.  Hist.  Nat.,  1881,  x.  50-53. 

f  Report  of  Progress  ;  Geol.  Survey  of  Canada,  1880,  -81,  -82,  p.  19  A. 


THE  TERRESTRIAL    PERIDOT ITES.  —  SERPENTI Ml.  157 

be  read  as  clearly  as  in  those  rocks  which  are  only  partially  altered.  The  picture  was 
there ;  the  polarized  light  served  as  the  developer  only.  Figures  5  and  6,  Plate  V.,  show 
the  structure  of  this  rock. 

1404,  from  the  same  locality  as  the  preceding,  is  a  greenish-  and  brownish-black  rock, 
with  lighter  greenish  spots,  and  coated  with  light  greenish  serpentine  on  "  slickenside  " 
surfaces. 

Section  :  a  yellowish  and  gray  mass  sprinkled  with  black  spots  of  iron  ore  and  in 
places  traversed  by  a  reticulated  network  of  the  same.  It  is  composed  principally  of 
serpentine  containing  crystals  and  granules  of  iron  ore,  besides  being  traversed  in  much 
of  its  mass  by  the  network  of  the  same.  It  is  also  stained  brownish-yellow  by  oxide  of 
iron.  In  portions  of  the  section  are  grayish  spots,  which  sometimes  show  in  their 
interior  greenish  grains.  These  interior  grains  are  remnants  of  the  original  olivine, 
while  the  gray  portions  are  formed  of  the  serpentinized  olivine  traversed  by  numerous 
fissures  filled  with  innumerable  dust-like  granules.  The  iron  ore  in  a  few  points  is  feebly 
translucent,  and  in  part  shows  no  metallic  reflection,  but  it  is  traversed  by  bands  that  do 
show  the  metallic  lustre.  Therefore  it  is  probably  a  mixture  of  chromite  and  magnetite, 
which  appear  to  be  commonly  associated  in  the  majority  of  serpentines.  The  general 
structure  is  represented  in  figure  5,  Plate  IV. 

1567  is  a  rock  that  in  the  hand  specimens  appears  to  be  the  same  as  No.  1404,  but  no 
sections  of  it  have  been  prepared. 

1563,  from  the  same  locality,*  is  very  similar  to  No.  1403,  but  is  more  altered  and 
weathered.     It  contains  chromite  and  talc.     It  has  a  yellowish-green  groundmass  of  ser- 
pentine traversed  by  innumerable  reticulated  veinlets  of  a  dark  green  to  black  serpentine. 
These  veinlets  give  a  structure  to  the  rock  that  might  be  taken  by  some  for  stratification. 

Section  :  a  grayish-green  mass  formed  of  translucent,  feebly  polarizing,  grayish,  finely 
granular  serpentiuous  material,  traversed  by  a  network  of  innumerable  veins  of  clear, 
more  or  less  brilliantly  polarizing  serpentine.  Much  chromite  occurs  in  irregular 
pronged  masses,  grains,  and  heaps  of  grains,  principally  arranged  along  the  serpentine 
veins.  While  some  may  be  original  or  else  picotite  altered  in  situ,  the  chief  portion 
appears  to  be  of  secondary  origin  in  the  serpentine. 

1564,  from  the  same  locality,  is  a  dark-greenish  rock  filled  with  talc  scales  and 
weathering  to  a  yellowish  rust-like  product,  with  the  talc  masses  protruding  from  the 
surface.     This  talc  forms  crystalline  masses  similar  to  those  formed  by  chlorite. 

The  section  is  an  irregular  mixture  of  pale  yellowish  serpentine  and  grayish-white 
talc  with  iron  ore.  The  ore  is  principally  associated  with  the  tfilc,  forming  bands  along 
the  cleavage  planes.  The  talc  plates  are  partly  isotropic  and  partly  feebly  polarizing, 
and  are  colorless  or  gray.  The  structure  and  relations  of  the  serpentine  and  talc  are  such 
as  to  indicate  that  the  serpentine  has  replaced  the  olivine,  and  the  talc  the  pyroxene 
minerals. 

Zoblitz,  Saxony. 

5001.  A  mixed  reticulated  greenish  and  brownish-red  rock,  containing  roundish 
reddish-black  to  black  spots. 

Section :  greenish-  and  brownish-red  with  grayish-black  spots.  The  principal  portion 
of  the  section  is  serpentine.  This  shows  the  reticulated  structure  in  common  and 
polarized  light,  frequently  having  between  the  colorless  meshes  greenish  patches  repre- 

*  All  the  High  Bridge,  New  Jersey,  serpentines  were  the  gift  of  Mr.  S.  II.  Dean. 


158  PERIDOTITE. 

senting  the  portions  of  the  olivine  last  altered.  In  some  portions  the  section  is  filled 
with  reticulated  veins  of  brown  and  cherry-red  hematite.  The  dark  spots  are  owing  to 
portions  being  filled  with  innumerable  granules  of  iron  ore,  arranged  about  some  central 
lines,  much  like  iron  filings  about  the  poles  of  a  magnet.  Talc  fibres  are  common. 
Chrysotile  veins  cut  the  section  in  various  directions. 

From  trail  beloiv  Chip  Flat,  Sierra  Co.,  Cal. 

45  P.  The  specimens  are  green  and  more  or  less  rubbed  or  "slickensided,"  as  are  the 
great  majority  of  serpentine  rocks.  The  only  section  is  of  a  pale  yellowish-green  color 
traversed  by  black  bands  of  iron  ore.  The  serpentine  shows  a  coarsely  aggregate  and 
fibrous  polarization,  and  appears  from  its  structure  to  replace,  in  part  at  least,  oliviue  and 
enstatite.  The  ore  crystals  are  octahedrons,  some  of  which  are  translucent  either  as  a 
whole  or  on  the  edges.  The  translucent  portions  are  reddish-brown,  and  the  opacity 
does  not  seem  to  depend  upon  the  size,  since  some  comparatively  large  crystals  are 
translucent,  while  very  minute  ones  are  often  opaque. 

40  P.  Similar  to  the  preceding.  This  rock  occurs  apparently  in  two  bands,  enclosing 
slate,  according  to  the  collector,  Professor  W.  H.  Pettee.* 

119  P.  is  of  similar  character.  In  the  interior  it  is  compact,  massive,  and  dark,  but 
on  the  exterior  smoothed  and  coated  with  greenish  and  light  greenish-yellow  serpentine. 

Depot  Hill,  near  Camptonville,  Sierra  Co.,  California. 

35  P.  A  compact  greenish-gray  rock  with  irregular  bluish-black  spots,  and  traversed 
by  chrysotile  veins. 

Section :  a  compact  grayish  and  greenish-yellow  mass,  composed  principally  of  ser- 
pentine with  iron  ore,  and  dolomite.  From  the  structure  of  the  serpentine  and  the 
arrangement  of  the  iron  ore,  it  is  probable  that  olivine  and  enstatite  were  former  con- 
stituents of  this  rock,  which  was  only  found  in  a  boulder,  f 

From  a  bell  four  hundred  feet  wide,  bettvecn  Whiskey  Diggings  and  Hepsidam, 

Plumas  Co.,  California. 

89  P.  A  bluish-black  and  greenish  mottled  rock,  showing  a  reticulated  structure. 
It  is  traversed  by  yellowish-green  serpentine  veins. 

Section  :  a  gray  groundmass  spotted  by  magnetite  and  traversed  by  veins  of  magne- 
tite and  yellow  serpentine.  The  groundmass  has  been  so  entirely  changed  to  serpentine, 
showing  the  usual  network  structure,  that  none  of  the  original  silicates  were  observed. 
So  far  as  can  be  judged  from  the  structure,  the  rock  originally  contained  olivine  and 
enstatite,  at  least.  Figure  5  of  Plate  VI.  shows  its  present  structure  and  the  serpentine 
veins  which  traverse  it.J 

Finland. 

According  to  Lagorio,  the  Finland  serpentine  forms  a  fibrous  mass  of  yellowish-gray 
to  green  color,  showing  the  usual  network  (Maschenstructur).  It  contains  no  olivine 
grains,  but  some  fissured  ones  of  dolomite  or  calcite.  The  microscopic  structure  is  very 
finely  fibrous,  and  it  forms  masses  in  a  limestone.  § 

*  Aurif.  Gravels,  p.  434.  f  Ibid.,  p.  429.  {  Ibid.,  p.  451. 

§  Micro.  Analyse  Oslbaltischer  Gebirgsarten,  187C,  p.  48. 


THE  TERRESTRIAL   PERIDOTITES. —  SERPENTINE.  159 

Klopfbcrg,  Austria. 

This  rock,  according  to  Dr.  F.  Becke,  is  a  light  greeu  to  dark  porous  soft  stone,  bearing 
long,  colorless  tremolite  crystals,  chrome-bearing  magnetic  ore,  and  numerous  soft  silver- 
white  talc  scales.  The  rock  is  greatly  altered,  and  in  the  section  shows  the  usual  net- 
work, arising  from  the  alteration  of  olivine,  which  in  the  darker  stone  still  exists  in  single 
grains,  but  in  the  light  greeu  specimens  the  oliviue  has  disappeared,  and  grains  of  a 
rhombic  carbonate  appear  in  its  place.* 

Nezcros,  Thcssaly. 

A  dark,  nearly  black  rock,  rich  in  chromite,  has  been  described  by  Dr.  F.  Becke  as 
showing  in  the  thin  section  the  usual  mesh  structure  formed  by  the  serpentine  and  iron 
ores.  It  also  contains  a  little  colorless  actinolite,  possessing  the  prismatic  cleavage  of 
hornblende.f 

Fatu  Tcmanu,  Timor. 

A  dark  bluish-green  rock  with  light  green  spots  and  magnetite  grains.  Microscopi- 
cally this  serpentine  evidently  was  derived  from  olivine,  and  it  shows  a  characteristic 
network  especially  marked  through  the  arrangement  of  the  ore  particles  which  form  the 
medial  lines.  Bordering  them  are  light  green  bands  enclosing  the  darker-colored  inter- 
stitial portion.  Much  chrysotile  occurs,  and  a  whitish-green  picrolite,  forming  in  the 
section  a  finely  fibrous  cloudy  mass.  J 

Four  miles  from  Wcstficld  Centre,  Wcstfield,  Massachusetts. 

1073.  Section :  greenish-yellow  with  grayish-white  spots,  and  traversed  by  an  irreg- 
ular network  formed  from  dust,  grains,  and  crystals  of  black  iron  ore.     The  serpentine  in 
polarized  light  shows  aggregate  and  fibrous  characters,  while  dolomite  occurs  sprinkled 
through  much  of  the  section's  mass.     The  grayish  spots  seem  to  be  formed  of  dolomite 
mixed  with  serpentine  and  talc. 

The  hand  specimen  is  a  dark  grayish-black  rock,  with  light  greenish  irregular  patches 
of  serpentine,  talc,  and  dolomite.  This  structure  is  similar  to  that  of  the  other  specimens, 
1074, 1075,  1076,  1077, 1078,  and  1079.  In  the  weathered  surface  forms  the  talc  is 
better  crystallized,  showing  its  normal  structure,  while  the  dolomite  is  more  abundant  and 
better  marked.  In  these  specimens  every  gradation  can  be  traced  between  the  liglit- 
greenish  serpentinous  coloid-like  masses  to  the  well-differentiated  aggregations  of  talc 
plates.  These  specimens  show  clearly  the  production  of  talc,  dolomite,  and  serpentine 
from  the  metamorphosis  of  peridotites. 

This  rock  (1073)  weathers  to  a  rough  deep-pitted  surface,  colored  grayish  and  coated 
with  lichens.  Here  the  difference  is  strongly  marked  between  the  internal  molecular 
alterations  and  the  superficial  surface  weathering. 

I  have  been  greatly  indebted  to  the  kindness  of  Mr.  S.  H.  Dean,  of  High  Bridge,  K  J., 
for  this  and  many  others  of  the  serpentines  of  Eastern  North  America  described  here. 

1074.  This  section  is  similar  to  that  of  No.  1073.     The  iron  ore  forms  in  places 

»  Min.  Mitth.,  18«2  (2),  iv.  341-343.  f  Min.  Mitth.,  1878  (1),  i.  470-472. 

{  Wichmann,  Jaarb.  Mijuw.  N.  0.  I.,  1882,  pp.  214-216. 


160  PERIDOTITE. 

quite  a  rectangular  grating,  and  much  talc  is  present  in  curved  and  bent  fibrous  masses. 
The  general  structure  of  this  section  is  shown  in  figure  2,  Plate  VII. 

1081,  also  from  Mr.  S.  H.  Dean,  was  obtained  by  him  from  the  bed  of  the  West- 
field  Paver  in  Eussell,  Massachusetts.  This  is  a  leek-green  serpentine,  containing 
grains  of  chromite  and  closely  resembling  that  from  Chester  and  Texas,  Pennsylvania. 
No  section. 

Lynnfield,  Massachusetts. 

1087.  Section  :  pale  yellowish-green,  mottled  with  spots  of  clear  grayish-white  and 
with  dust  and  grains  of  iron  ore.  In  common  light  under  the  microscope,  the  greenish 
portion  shows  the  dirty  green  spots  commonly  seen,  formed  from  the  alteration  of  the 
unfissured  central  portion  of  the  oliviue  grains.  In  polarized  light  it  shows  the  common 
reticulated  meshwork  of  most  alteration  serpentine.  The  clear  grayish-white  portions  are 
formed  of  interlacing  and  divergent  fibres  and  plates,  optically  orthorhombic,  and  polar- 
izing with  clear,  beautiful  tints,  varying  from  yellowish-white  to  yellow  and  red.  The 
iron  ore  is  crystalline  granular,  opaque,  has  but  little  lustre,  and  resembles  chromite. 
The  forms  of  the  larger  grains  resemble  those  of  picotite  when  only  partially  altered. 
The  general  structure  is  shown  in  Plate  VI.  figure  2. 

The  hand  specimen  is  a  dark  grayish-green  compact  rock,  mottled  with  black  iron  ore 
and  talc  scales.  This  specimen  was  kindly  presented  to  the  collection  by  Professor  N.  S. 
Shaler.  Later  the  locality  has  been  visited  by  Professor  J.  D.  Whitney  and  myself,  and 
other  specimens  answering  in  general  characters  to  the  above  were  obtained.  While  this 
serpentine  is  much  jointed,  no  evidence  of  stratification  was  seen,  and  it  was  apparent 
that  the  approximately  parallel  jointing  had  been  taken  for  stratification  by  previous 
observers.  No  contacts  with  the  adjacent  rock  could  be  found.  In  a  pit  near  the  quarry 
the  rock  is  a  mottled  dark  grayish-black  one,  which  in  thin  splinters  is  dark  green. 

A  serpentine  of  much  finer  quality  and  of  a  dark  green  color,  was  found  outcropping 
by  the  side  of  the  road  to  the  northwest.  A  dark  green  much  broken  and  Assured  ser- 
pentine outcrops  opposite  C.  W.  Hersey's  blacksmith's  shop,  in  Peabody,  on  the  road 
near  the  line  between  that  town  and  Lynnfield.  While  no  definite  field  evidence  regard- 
ing its  origin  could  be  obtained,  the  general  appearance  of  the  outcrops  was  that  of  an 
eruptive  mass  metamorphosed,  nothing  being  observed  that  indicated  either  chemical  or 
mechanical  sedimentation.* 

The  Lynnfield  serpentine  shows  when  tested  the  presence  of  chromium,  and  the  rock 
powder  is  magnetic. 


From  the  road  betiveen  La  Vega  and  Jarabacoa,  at  the  first  crossing  of  the  River  Joa 
going  from  the  former  town,  Province  of  La  Vega,  San  Domingo. 

141  G.  This  is  a  much  altered  foliated  rock,  composed  essentially  of  light  greenish- 
white  and  yellowish  darker  green  serpentine.  The  foliated  structure  appears  to  be 
entirely  due  to  the  alteration  and  pressure  to  which  the  rock  has  been  subjected.  No 
section  was  made  of  this  rock.  Collected  by  W.  M.  Gabb. 

«  See  also  Crosby,  Occas.  Papers,  Bost.  Soe.  Nat.  Hist.,  1880,  iii.  115  ;  Hitchcock,  Final  Report, 
Geol.  Mass.,  1841,  p.  159. 


THE   TERRESTRIAL   PERIDOTITES.  —  TORODITE.  101 

Neti'port,  Vermont. 

95.  This  rock  was  collected  by  Mr.  J.  H.  Huntington,  near  Mr.  C.  Gilpin's  residence. 
It  is  a  grayish-green  rock  having  a  greenish  serpentine  groundmass,  holding  grayish  and 
brownish  masses  and  crystals  of  a  ferruginous  carbonate,  showing  well-marked  rhombohe- 
dral  cleavage. 

Section :  a  gray  mass  traversed  and  sprinkled  with  black  iron  ore.  Composed  of  a 
coarsely  fibrous  serpentine,  a  dirty  gray,  feebly  polarizing  carbonate  showing  well-marked 
rhombohedral  cleavage,  and  iron  ore.  The  serpentine  forms  the  principal  portion  of  the 
section. 

Cclinac,  Austria. 

A  light-green  rock  containing  dark  particles  of  amorphous  silica.  The  section  shows 
the  usual  network  of  serpentine  with  isotropic  silica  and  picotite.* 

Texas,  Pennsylvania. 

A  clear  leek-green  serpentine,  obtained  from  W.  J.  Knowlton,  169  Tremont  Street, 
Boston,  containing  chromic  iron  in  veins  and  crystals,  or  scattered  granules. 

Section :  clear  and  grayish-white,  with  black  spots  of  chromic  iron.  The  clear  portions 
show  the  fibrous  polarization  of  serpentine,  some  of  the  fibres  being  distinctly  optically 
orthorhombic  in  character.  In  the  grayish  portion  lie  plates  and  fibres  of  tremolite ; 
while  the  chromite  is  opaque  in  transmitted  light,  except  in  the  thinnest  portions,  which 
are  translucent  and  reddish-brown.  By  reflected  light  the  grains  are  dull,  and  without 
lustre.  The  larger  grains  are  traversed  by  fissures  filled  with  serpentine.  A  grain  of 
pyrite  was  observed. 

Cluster,  Pennsylvania. 

1487.  A  clear  leek-green  compact  rock  containing  grains  of  chromite.  Weathers 
yellowish  and  greenish-gray.  Section:  clear  grayish- white  fibrous  mass  showing  the 
usual  aggregate  fibrous  polarization. 

This  and  the  preceding  one  show  the  extreme  change  in  rocks  to  pure  serpentine. 


VARIETY.  —  Porodite. 

Fatu  Luka,  Timor. 

Large,  rounded  pieces  of  serpentine  cemented  by  pale-whitish  and  finely  sphemlitic 
opal  and  a  greenish  paste.  The  serpentine  is  yellowish  and  grass-green,  and  shows  the 
mesh  structure.  The  history  of  these  altered  fragments  is  summed  up  by  Wichmann 
as  follows:  —  1.  The  formation  of  the  peridotite.  2.  The  formation  of  the  serpen- 
tine, including  the  separation  of  the  iron  ore  and  the  beginning  of  the  Masclicnstructur. 
3.  The  decomposition  of  the  iron  ore  and  the  formation  of  the  yellow  network.  4.  The 
impregnation  of  the  interstitial  portion  with  the  alteration-product,  —  chromite.  5.  The 
alteration  of  the  exterior  into  a  finely  fibrous  compact  gray  substance. 

The  cement  is  mostly  serpentine  with  a  fine  scaly  material.! 


•  C.  v.  John.  Jalir.  Geol.  Reichs.,  1880,  xxx.  448.  f  Jaark  Mijnw.  N.  0.  I.,  1882,  pp.  216-222. 

21 


162  PERIDOTITE. 

Strand,  Timor. 

Another  porodite  of  similar  character  was  described  by  Wichmann  as  a  greatly  decom- 
posed fragmental  rock,  composed  of  rounded  and  angular  fragments  of  dirty-brown  and 
brownish-green  serpentine,  cemented  by  a  sometimes  lighter,  sometimes  darker,  dirty- 
brown  and  greenish-brown  mass.  Microscopically  this  serpentine  is  similar  to  the  pre- 
ceding, but  is  more  altered.  The  interior  portion  of  some  of  the  grains  is  filled  with  a 
dirty-brown  hydrated  oxide  of  iron. 

Another  porodite  from  Fatu  Luka,  Timor,  was  described  by  the  same  author  as  a  dirty 
light-brown  and  brownish-green  tufaceous  rock  with  numerous  serpentine  and  pluestine 
(eustatite)  fragments.  The  rock  effervesces  feebly  with  acid.  The  serpentine  shows 
under  the  microscope  a  network  structure  especially  of  the  iron  ore,  while  the  interior 
grains  are  greenish.  A  somewhat  altered  bronzite  containing  ore  grains  occurs.  The 
cement  is  of  a  brownish  shade,  homogeneous  and  isotropic.* 


SECTION  V.  —  Peridotite.  —  Its  Macroscopic  Characters. 

THE  meteoric  forms  show  in  general  a  fine,  more  or  less  granular  ground- 
mass  of  some  shade  of  gray  —  varying  from  a  light  gray  or  grayish-white  to 
a  bluish  or  dark  gray.  Often  they  are  porphyritic  from  enclosed  chondri, 
pyrrhotite,  and  metallic  iron.  Again  they  are  apt  to  show  brownish-yellow 
spots  of  ferruginous  staining,  owing  to  the  oxidation  of  the  iron  ores.  The 
grayish  color  appears  to  be  mainly  due  to  the  finely  divided  state  of  the 
component  silicates,  as  well  as  to  the  natural  Color  of  the  base  and  the  en- 
statite.  The  olivine  is  in  too  minute  grains  to  show  its  characteristic 
color,  except  in  rare  cases.  The  chondri  frequently  appear  as  gray,  brown, 
bluish,  and  white  grains  in  the  groundmass,  giving  the  appearance  of  a 
fragmental  structure  to  the  rock. 

The  completely  or  coarsely  crystalline  forms,  like  those  from  Estherville 
and  Chassigny,  present  a  gray  to  pale  yellow  crystalline  mass  closely 
resembling  that  of  the  least  altered  terrestrial  peridotites  if  not  identical 
with  it. 

The  iron  ores  occur  as  irregular  masses,  sometimes  of  a  semi-sponge-like 
structure,  and  in  the  form  of  metallic  iron,  pyrrhotite,  chromite,  and 
magnetite. 

While  the  silicates  are  not  usually  sufficiently  distinct  to  be  determined 
macroscopically,  yet  they  sometimes  are,  and  olivine  in  such  cases  shows  in 
pale  green  or  yellowish  grains,  having  a  conchoidal  fracture  and  the 
same  general  characters  this  mineral  has  when  it  is  of  terrestrial  origin. 

«  Jaarb.  Mijuw.  N.  0.  I.,  1882,  pp.  216-222. 


ITS   MACROSCOPIC   CHARACTERS.  163 

It  has  been  above  stated  that  the  least  altered  of  the  terrestrial  peri- 
dotites  present  an  appearance  and  structure  essentially  similar  to  the 
meterorite  of  Chassigny  and  the  portions  of  that  from  Estherville  which 
are  comparatively  free  from  iron.  They  are  of  a  grayish-green  or  green 
color,  crystalline  granular  in  structure,  and  usually  contain  more  or  less 
dark  grains  of  picotite  or  some  iron  ore,  disseminated  throughout  the  mass. 
The  first  traces  of  change  are  in  coloration,  passing  from  a  green  to  a 
yellowish-green,  yellowish,  and  to  a  yellowish-  or  rnsty-brown.  The  rocks 
.are  more  or  less  vitreous  or  greasy  in  lustre.  With  increasing  altera- 
tion, a  reddish-brown  to  grayish-brown  color  predominates  ;  and  this 
finally  passes  into  a  dark  greenish-black  to  black  compact  rock,  somewhat 
resembling  the  basalts,  but  of  a  duller  color,  more  resinous  lustre, 
and  more  compact,  as  well  as  of  a  higher  specific  gravity  and  less 
hardness. 

The  crystalline  granular  groundmass  of  olivine  or  serpentine  may  or  may 
not  porphyritically  enclose  crystals  and  grains  of  enstatite,  diallage,  and 
augite.  These  minerals  usually  appear  as  greenish,  grayish,  or  bronze-like 
crystals  and  grains  scattered  in  the  rock.  They  commonly  weather  to 
bronze-like,  more  or  less  cleavable  and  platy  forms ;  and  even  on  the  fresh 
fracture  of  some  specimens  show  in  certain  lights  as  an  irregular  network, 
brightly  reflecting  the  light,  and  holding  in  its  meshes  the  dark-greenish 
altered  olivine. 

The  olivine  groundmass  when  altered  presents  under  the  lens  the  appear- 
ance of  yellowish  or  grayish  granules  cut  and  surrounded  by  a  fine  reticu- 
lated network  of  a  darker  material  (serpentine) ;  but  when  the  change 
has  progressed  further,  the  groundmass  becomes  compact  and  apparently 
homogeneous. 

As  the  more  highly  altered  states  are  reached,  the  variations  in  the 
macroscopic  appearance  become  exceedingly  numerous  ;  so  much  so,  that 
only  a  few  of  them  can  be  mentioned  here.  The  color  generally  is  some 
shade  of  green,  varying  from  a  dark  green  or  greenish-black  to  a  yellowish- 
green.  Sometimes  it  is  reddish  (brownish-  or  cherry-red),  owing  to  the  state 
of  its  ferruginous  contents.  The  pyroxene  minerals,  when  occurring,  vary 
in  amount  of  alteration  from  the  porphyritically  sprinkled  bronze-  or  copper- 
like  crystals  to  silvery-white,  and  to  grayish  and  greenish  forms,  which  in 
turn  pass  into  patches  of  serpentine  of  .a  deeper  green  color  and  more 
compact  texture  than  the  groundmass,  but  which  finally  become  completely 


164  PERIDOTITE. 

blended  with,  and  entirely  lost  in,  the  serpentine  groundmass.  Oftentimes 
the  pyroxene  minerals  are  replaced  by  greenish  to  whitish  talcose  material 
and  talc  scales.  In  the  process  of  alteration,  segregations  of  serpentine, 
dolomite,  magnetite,  chromite,  etc.,  occur,  giving  rise  to  veins  of  serpentine 
(chrysotile)  and  to  veins  and  nodular  masses  of  dolomite  and  iron  ores  lying 
in  or  traversing  the-serpentinous  groundmass. 

However  dark  the  altered  peridotites  may  be  in  color,  the  thin  splinters, 
as  a  rule,  are  translucent  and  transmit  a  greenish  or  yellowish  light.  The 
more  or  less  serpentinized  peridotites  are  traversed  by  fissures,  which  are 
most  abundant  in  those  entirely  changed  to  serpentine.  The  sides  of 
these  fissures  usually  are  polished  or  coated  with  serpentine,  talc,  etc., 
forming  "  slickensides " ;  which,  it  is  conceived,  may  have  some  connection 
with  the  chemical  alteration  of  the  rock  itself. 

Amongst  the  various  forms  produced  by  the  extreme  changes  are  a 
yellowish,  more  or  less  gummy-looking  substance,  and  a  grayish,  yellowish, 
to  chrome-green  translucent  serpentine.  While  these  are  oftentimes  pro- 
duced from  the  alteration  of  the  rock  in  situ,  they  also  appear  to  be  formed 
by  migrated  serpentinous  material,  and  in  such  cases  to  belong  to  the  vein- 
stones. These  secondary  massive  products  contain  more  or  less  iron  ore 
in  the  form  of  chromite  or  magnetite.  It  is  to  these  nearly  pure  serpen- 
tines, which  result  from  the  complete  change  or  migration  of  the  material, 
that  the  term  serpentine,  as  it  is  used  in  works  on  mineralogy,  properly  applies. 
But  from  the  general  and  microscopic  characters  of  the  material  known  as 
serpentine  in  lithology,  it  would  appear  that  under  that  name  is  placed  a 
mineral  of  variable  composition,  forming  a  series  like  feldspar  or  pyroxene, 
or  else  several  distinct  minerals  are  now  so  placed. 

Further,  in  the  process  of  alteration  there  often  results  a  fissile  or  schis- 
tose structure,  giving  rise  to  a  pseudo-lamination.  In  part  this  seems  to  be 
owing  to  the  segregation  of  chrysotile,  serpentine,  iron  ores,  dolomite,  etc., 
in  approximately  parallel  lines ;  and  in  this  case  the  fissility  is  often  only 
apparent  and  not  real.  Sometimes  the  schistosity  seems  to  be  due  to  pres- 
sure during  the  time  of  alteration.  Occasionally  the  rock  has  a  brecciated  or 
conglomerate  structure,  owing  to  the  vein  serpentine  or  dolomite  surround- 
ing less  altered  portions  of  the  rock.  With  the  formation  of  talc  or  actinolite 
in  these  altered  peridotites,  the  transition  to  a  true  schist  is  evinced  by 
various  gradations,  until  a  true  talc  schist  or  actinolite  schist  results.  These 
schists  are  greenish  in  their  normal  condition,  but  often  through  decom- 


ITS   MICROSCOPIC   CHARACTERS.  165 

position  of  the  iron,  become  stained  and  present  a  rusty  brown  and  gray 
aspect  closely  simulating  many  mica  schists. 

Owing  to  the  production  of  dolomite,  there  results,  in  part  at  least, 
ophicnlcites  and  dolomitic  limestones  —  the  purity  depending  on  the  amount 
of  alteration,  and  on  the  materials  both  carried  into  and  removed  from  the 
rock  during  the  process  of  alteration.  These  dolomitic  limestones  are  usually 
gray,  green,  or  yellow,  but  sometimes  of  quite  a  clear  grayish-white  color, 
and  crystalline  in  structure.  In  the  above,  only  a  portion  of  the  various 
forms  produced  in  the  process  of  alteration  so  common  in  peridotic  rocks 
could  be  mentioned ;  but  it  is  hoped  that  enough  has  been  given  to  afford 
some  idea  of  the  general  appearance  of  these  rocks  macroscopically. 

Of  necessity,  from  the  mode  of  origin  of  the  peridotites  and  their  ex- 
posure to  detrital  agencies,  various  detrital  or  poroditic  forms  must  result. 
Undoubtedly,  when  they  are  re-consolidated,  it  is  exceedingly  difficult  to 
distinguish  these  true  breccias,  conglomerates,  and  sandstones  from  the 
pseudo-fragmental  forms  of  similar  structure  that  are  produced  in  this  rock 
species,  as  in  every  other,  by  the  filling  of  fissures,  or  by  the  dissolving  of 
portions  of  the  rock  and  their  replacement  by  other  material,  while  intersti- 
tial portions  of  the  rock  remain  in  situ.  The  poroditic  forms  of  the  peridotites, 
so  far  as  now  known,  are  all  of  a  serpentinous  character,  having  been 
greatly  altered ;  but  it  is  suspected,  and  in  many  cases  claimed,  that  other 
forms  are  of  like  detrital  origin ;  however,  conclusive  proof  of  this  is  still 


wanting. 


It  is  probable  that  part  of  our  ophicalcites  and  brecciated  serpentines  are 
of  a  poroditic  origin,  while  others  appear  to  have  been  produced  by  changes 
in  the  massive  rock  in  siiu;  that  is,  they  do  not  properly  belong  to  the 
fragmental  rocks  to  which  they  are  generally  iissigned.  It  is  proposed  here 
to  distinguish  these  falsely  appearing  detrital  forms  by  the  terms  pseudo- 
breccias,  conglomerates,  and  sandstones ;  or,  collectively,  as  pseudo-frag- 
mental or  detrital  rocks ;  or,  better  still,  by  the  introduction  of  the  term 
merolile  (/u.e'pos,  Xi#os),  and  its  adjective  form  merolitic,  for  them,  since  they 
are  composed  of  detached  portions  of  the  same  rock. 

SECTION   VI.  —  Peridottte.  —  Its  Microscopic  Clm-aelers. 

Br.oixxixr,  with  the  meteoric  peridotites,  the  first  variety  is  composed 
of  rounded  fissured  oliviue  grains  with  brownish  glass  inclusions,  brown- 


166  PEEIDOTITE. 

ish  interstitial  glass,  and  scattered  crystals  of  chromite.  In  the  next  type 
enstatite  enters  as  a  constituent,  and  the  chondritic  structure  appears.  The 
groundmass  is  of  a  grayish  color  sprinkled  with  iron,  pyrrhotite,  and 
brownish  ferruginous  spots ;  and  is  composed  of  grains  and  crystals  of 
olivine,  enstatite,  chromite,  iron,  and  base,  enclosing  larger  masses  of  these 
minerals  and  chondri.  The  base  is  fibrous-granular  in  structure,  and  varies 
from  a  light  to  a  dark  ash-gray,  while  it  occurs  with  every  gradation,  from 
that  not  affecting  polarized  light  to  that  in  which  the  differentiation  has 
been  carried  to  such  an  extent  that  it  shows  a  feeble  coloration  in  this  light, 
and  at  best  is  only  a  semi-base.  The  chondri  are  composed  of  olivine  and 
base,  enstatite  and  base,  and  enstatite,  olivine,  and  base;  all  being  more 
or  less  associated  with  iron  ores,  and  generally  passing  gradually  into 
the  adjoining  groundmass.  The  olivine  chondri  usually  contain  a  darker 
base  than  the  enstatite  chondri,  and  are  composed  of  grains  and  crystals  of 
olivine  cemented  by  the  base,  which  in  some  cases  produces  forms  some- 
what resembling  organized  structures  (Plate  II.  figure  4).  The  enstatite 
chondri  show,  like  the  olivine  ones,  a  more  or  less  spherical  form.  The 
enstatite  chondri  are  usually  composed  of  fan-like,  eccentrically  radiating 
ribs  of  enstatite  cemented  by  the  lighter  gray  fibrous  base,  and  they 
sometimes  simulate  -superficially  certain  organized  structures  (Plate  II.  fig- 
ure 6;  Plate  III.  figure  1).  The  olivine  and  enstatite  chondri  are  composed 
of  granules  and  crystals  of  enstatite  and  olivine  cemented  by  the  base 
(Plate  II.  figure  5). 

The  olivine  of  the  meteorites  is  usually  clear  or  pale  greenish,  although 
often  stained  by  ferruginous  material  along  its  fissures.  It  is  more  or 
less  fissured,  contains  inclusions  of  glass  and  iron  ores,  and  generally  is 
in  rounded  grains,  and  but  rarely  in  well-defined  crystals. 

The  enstatite  is  in  grains  and  crystals,  which  are  clear  and  transparent, 
but  which  sometimes  display  a  faint  green  tinge,  and  contain  glass  inclu- 
sions. The  mineral  shows  as  a  rule  one  longitudinal  approximately  parallel 
cleavage,  with  sometimes  another  —  or  a  cross  fracture  —  at  right  angles 
to  the  first  cleavage  (Plate  III.  figure  6).  The  iron  is  in  irregular  grains, 
having  in  the  section  in  reflected  light  an  appearance  nearly  like  ground 
steel  (Plate  II.  figures  4,  5,  6 ;  Plate  III.  figure  3).  Sometimes  the  iron  is 
quite  dark,  and  is  united  with  pyrrhotite  and  possibly  magnetite  (Plate  III. 
figures  2,  3,  4,  5,  6  ;  Plate  IV.  figure  1).  The  pyrrhotite  shows  a  dark  bronze 
color  and  a  rough  granulated  surface  in  reflected  light,  and  frequently  sur- 


ITS   MICROSCOPIC   CHARACTERS.  167 

rounds  grains  of  metallic  iron  (Plate  III.  figure  3).  The  common  ferrugi- 
nous staining  and  the  granular  structure  of  the  groundmass  is  shown  to  a 
greater  or  less  extent  in  all  the  figures  of  meteoric  peridotites  given  in  the 
plates. 

The  chromite  or  picotite  occurs  in  dark-brown  to  black,  opaque  to  trans- 
lucent grains  and  octahedrons. 

An  entirely  crystalline  form  of  saxonite  occurs  in  the  Manbhoom  (India) 
meteorite,  which  Tschcrmak  has  described  as  composed  of  a  greenish-yellow 
granular  mixture,  in  which  bronzite  and  olivine  have  a  nearly  equal  color. 
Besides  these,  there  are  numerous  grains  of  pyrrhotite  and  little  "grains  of 
iron.  In  the  thin  section  granular  olivine  is  seen  to  be  the  principal  consti- 
tuent. This  is  traversed  by  fissures,  and  has  few  inclusions.  Bronzite  occurs 
in  rounded  or  elongated  grains,  with  a  fibrous  structure,  and  both  it  and  the 
olivine  have  a  pale-green  color.  Further,  the  rock  contains  colorless  grains 
of  plagioclase  (?)  and  roundish  opaque  pyrrhotite  and  iron  grains.* 

The  next  variety  is  formed  by  the  addition  of  diallage,  but  otherwise  the 
structure  remains  the  same.  The  diallage  shows  not  only  the  common  lon- 
gitudinal cleavage,  but  it  is  also  much  cut  by  an  irregular  augitic  cleavage, 
thus  enabling  its  ready  separation  from  enstatite  in  some  cases.  It  other- 
wise is  closely  like  the  enstatite  in  its  general  characters  and  in  its  inclu- 
sions (Plate  III.  figures  5,  6). 

Sometimes  the  Iherzolite  variety  of  the  meteoric  peridotites  is  found  to  be . 
entirely  crystalline,  and  in  this  case  the  chondri  and  base  are  wanting,  and 
the  rock  is  composed  of  a  crystalline  granular  aggregate  of  olivine,  enstatite, 
diallage,  iron,  pyrrhotite,  and  chromite.  In  this  the  olivine  contains  irreg- 
ular masses  and  globules  of  iron ;  while  the  enstatite  and  diallage  have  the 
same  inclusions,  not  only  of  iron,  but  also  of  olivine  grains. 

In  the  next  type  augite  is  added,  but  it  makes  no  essential  change  in  the 
general  characters  of  the  rock.  In  some  of  the  peridotic  meteorites,  plagio- 
clastic  and  possibly  orthoclastic  feldspar,  peckhamite,  schreibersite,  graphite, 
etc.,  occur  in  subordinate  quantities. 

The  microscopic  study  of  meteorites  is  yet  so  incomplete  that  it  is  pos- 
sible that  other  types  and  characters  may  be  later  added. 

In  two  cases  a  fragmental  or  brecciated  structure  has  been  seen,  giving 
us  tufaceous  meteorites,  which,  otherwise  than  this,  show  the  common  chon- 
dritic  characters. 

»  Die  mikros.  Bcsch.  mcteoriten,  1S83,  i.  10;  Site.  Wien.  Akad.,  1883,  Ixxxviii.  (}J,  302,  363. 


168  PEEIDOTITE. 

In  the  terrestrial  peridotites  we  commence  with  dunitc  —  a  clear  granular 
mass  of  fissured  olivine  grains,  which  are  either  colorless  or  slightly  tinged 
yellow  or  green.  Sprinkled  through  the  olivine  mass  are  dark  to  brownish, 
opaque  to  translucent,  grains  and  crystals  of  chromite  or  picotite,  and  mag- 
netite, as  well  as  sometimes  a  few  enstatite  plates,  either  colorless  or  of  a 
greenish  tinge  (Plate  IV.  figure  2). 

In  these  a  gradual  change  to  serpentine  begins  by  its  production  along 
the  fissures  of  the  olivine,  forming  a  yellowish  or  greenish  network,  and  this 
change  goes  on  until  the  olivine  is  completely  altered,  and  only  the  network 
structure  remains  (Plate  IV.  figures  3,  4 ;  Plate  V.  figures  1,  2,  4 ;  Plate 
VI.  figure  2).  Again  the  change  extends  so  far  that  not  even  this  trace 
of  the  original  structure  remains  (Plate  VI.  figures  5,  6;  Plate  VII.  figure  2). 
In  the  process  of  alteration  to  serpentine,  that  formed  first  along  the  fissures 
generally  takes  a  different  structure  and  color  from  that  later  produced  by 
the  alteration  of  the  interior  portion  of  the  olivine  grains  —  thus  showing 
two,  and  sometimes  three,  stages  in  the  progress  of  alteration.  While  the 
mode  of  alteration  is  thus  conspicuous  in  the  earlier  stages,  the  final  result 
is  to  produce  a  pure,  clear,  homogeneous  serpentine,  of  a  uniform  yellowish 
or  greenish  tint,  or  even  colorless ;  in  which  no  trace  remains  of  the  original 
structure,  to  tell  its  derivation.  The  proof  of  these  changes  is  found  in  fol- 
lowing out  the  various  gradations  in  the  different  peridotites,  particularly 
in  different  portions  of  the  same  rock-mass. 

By  the  gradual  increase  in  the  amount  of  enstatite  present,  we  pass  into 
the  succeeding  variety  —  saxonite,  and  this  again,  by  the  addition  of  diallage, 
gradually  passes  into  the  llierzoliie  variety,  and  this  into  the  succeeding  form 
(buchncrite)  by  the  addition  of  augite.  Again,  we  pass  gradually  to  those 
forms  in  which  the  enstatite  has  disappeared,  and  only  diallage  (eiilysitc}  or 
augite  (picrite)  remains  with  the  olivine  to  form  the  rock.  Every  gradation 
exists  between  these  forms,  and  they  are  closely  allied  in  physical  and 
chemical  characters. 

The  enstatite  appears  as  a  clear,  colorless  mineral,  or  else  as  one  slightly 
tinged  with  green.  Sometimes  it  occupies  a  subordinate  portion  of  the  rock, 
then  again  it  forms  the  chief  part,  holding  the  olivine  inclosed  in  and 
subordinate  to  it.  The  enstatite  is  sometimes  feebly  pleochroic,  and  shows 
a  well-marked  longitudinal  cleavage ;  the  development  of  which,  instead  of 
forming  a  smooth  fracture,  usually  occasions  the  tearing  of  a  rough  line, 
with  stringy  fibres  extending  from  one  side  to  the  other.  Besides  the  longi- 


ITS   MICROSCOPIC   CHARACTERS.  169 

tudinal  cleavage,  a  cross  fracture,  at  right  angles  to  the  principal  cleavage, 
is  often  present. 

The  diallage  possesses  similar  characters  to  the  enstatite,  and  generally  is 
undistinguishable  from  the  latter  except  optically,  but  sometimes  it  shows  two 
cleavages  approaching  those  of  augite,  breaking  the  surface  into  rough,  irregu- 
lar rhombs,  which  serve  to  distinguish  the  diallage  in  question  from  enstatite. 
Again,  diallage  has  not  only  its  proper  longitudinal  cleavage,  but  also  the 
well-marked  cleavage  of  augite.  This  fact  indicates  that  there  is  no  real  dis- 
tinction between  diallage  and  augite,  but  both  form  a  continuous  series. 

The  augite  is  pale-yellow  or  brown,  shows  its  characteristic  cleavage,  and 
is  sometimes  feebly  pleochroic.  It  occurs  in  grains  and  crystals,  and  some- 
times encloses  olivine  grains. 

Since  the  olivine,  octahedral  oxides,  and  their  alteration-products  in  the 
varieties  of  peridotite  are  like  those  in  the  first-described  variety,  it  remains 
simply  to  trace  the  alterations  in  these  varieties  as  they  are  modified  by 
the  addition  of  other  minerals  than  olivine.  The  pyroxene  minerals,  as 
a  rule,  are  less  liable  to  alteration  than  olivine,  and  are  frequently  deter- 
minable  after  the  olivine  has  been  entirely  changed.  This  is  indicated  in 
Plate  IV.  figure  6,  and  in  Plate  VI.  figures  3  and  4.  The  enstatite  usually 
shows  its  alteration  by  the  formation  of  a  greenish  product  along  its  cleavage 
planes  (Plate  V.  figure  3;  Plate  VII.  figure  1).  As  the  alteration  progresses, 
the  pyroxene  minerals  are  transformed  into  a  yellowish  or  grayish  serpen- 
tinous  mass,  which  may  show  aggregate  polarization,  or  may  retain  that  of 
the  mineral  from  which  it  has  been  derived. 

The  various  changes  in  the  peridotites  can  perhaps  be  best  followed  from 
the  plates.  In  Plate  IV.,  figure  1  indicates  a  typical  dunite  composed  of 
unchanged  olivine  grains,  with  only  a  cloudiness  produced  by  the  fissures  by 
•which  the  mass  is  traversed.  Figure  3  shows  another  dunite  containing 
brown  picotites  and  exhibiting  the  formation  of  greenish  and  yellowish  ser- 
pentine along  the  fissures  of  the  olivine,  with  sometimes  a  complete  serpen- 
tinization  of  the  interstitial  olivine  grains.  Figure  4  shows  a  saxonite  in 
which  the  alteration  to  greenish  serpentine  has  progressed  so  far  as  to  leave 
only  a  subordinate  portion  of  clear  olivine  grains  untouched.  Part  of  the 
enstatite  has  been  changed  to  serpentine,  while  part  is  only  partially  altered, 
as  shown  in  the  upper  left-hand  portion  of  the  figure. 

In  Plate  V.  figure  1,  is  shown  the  commencement  of  alteration  in  a  Iher- 

zolite,  in  which  the  olivine  and  pyroxene  minerals  assume  a  gray  tinge,  and 

22 


170  PERIDOTITE. 

the  whole  mass  is  traversed  by  brown  veins  bearing  iron  dust  along  the 
medial  line.  Figure  2  shows  further  progress  in  the  change  ;  the  brown 
veins  increase  in  number  and  strength,  and  the  ferruginous  medial  line 
becomes  more  strongly  marked.  Bordering  these  veins  are  bands  of  yellow 
serpentine,  which  in  their  turn  are  fringed  on  the  inner  side  by  orange, 
yellow,  and  brown  serpentine,  which  again  encloses  grains  of  the  still  un- 
altered olivine.  In  figure  4  the  change  has  progressed  still  further.  The 
same  brown  veins  with  their  ferruginous  backbone  are  to  be  seen,  but  the 
yellow  serpentine  has  engrossed  the  remainder,  cutting  out  the  orange-yel- 
low serpentine  and  the  still  unchanged  olivine  grains  seen  in  figure  2. 
Towards  the  base  of  figure  4  and  on  the  right  and  left  are  to  be  seen  the 
remains  of  two  partly-altered  grayish  pyroxenes.  Plate  VI.  figure  4  shows 
a  still  further  change;  in  which  the  brown  veins  and  the  interstitial  por- 
tions are  only  distinguished  by  slight  shades  of  color.,  Inclosed  in  this  is  an 
enstatite,  which  retains  its  characteristic  optical  characters,  but  still  it  is 
altered  and  filled  in  by  magnetite  grains,  which  have  separated  out  during 
the  process  of  alteration.  Figure  2  shows  still  farther  change,  in  which 
the  brown  veins  are  only  represented  by  their  intermedial  line  of  magnetite 
dust,  which  is  bordered  by  a  pale-yellowish  or  nearly  colorless  serpentine, 
holding  interstitial  rounded  patches  of  serpentine,  representing  the  last- 
altered  olivine  cores. 

Plate  V.  figure  3  shows  the  mode  of  alteration  in  the  enstatite,  taken 
from  the  same  section  as  figure  2.  At  the  left  and  right  of  the  upper  por- 
tion of  the  figure  are  to  be  observed  portions  of  the  altered  olivine  mass  as 
shown  in  figure  2,  while  a  yellowish  serpentine  vein  joins  the  two  parts, 
and  cuts  the  enstatite.  Along  the  cleavage-planes  of  the  enstatite  the 
greenish  and  yellowish  secondary  product  extends,  while  the  interme- 
diary portions  are  unchanged.  Plate  VII.  figure  1  represents  a  still  greater 
change  in  a  crystal  of  enstatite  from  the  same  section.  The  colors  are 
deeper,  and  fewer  unchanged,  intermediary  portions  exist,  while  the  cross 
cleavage  is  well  shown  by  the  yellowish-green  serpentine  bands  following 
its  planes. 

In  Plate  V.  figure  5,  we  see  the  remains  of  serpentinized  diallage  crys- 
tals, showing  optically  the  characters  of  serpentine  surrounded  by  brown 
bands  and  all  inclosed  in  pale-yellow  and  colorless  serpentine.  In  figure  6  is 
shown  another  portion  of  the  same  section,  in  which  the  change  has  proceeded 
to  a  greater  extent,  leaving  only  the  brown  serpentinous  masses  to  represent 


ITS   MICROSCOPIC   CHARACTERS.  171 

the  altered  minerals.  Figure  1,  Plate  VI.,  shows  a  similar  change.  The 
figure  at  its  base  possesses  a  character  similar  to  that  of  figure  4,  but  in  the 
remaining  portion  is  composed  of  clear,  colorless  serpentine,  holding  iron  ores 
and  yellowish  serpentine  pseudomorphs  after  olivine  grains. 

Figure  3  represents  a  serpentinized  peridotite  containing  rejected  iron  ores 
and  in  the  central  portion  the  remains  of  enstatite  crystals.  In  figure  5  we 
have  an  entire  alteration  of  the  rock  to  a  light  or  colorless  serpentine,  filled 
with  the  precipitated  iron  ores,  and  traversed  by  yellow  veins  of  serpentine. 
In  figure  6  is  to  be  seen  a  portion  of  the  same  section  as  that  shown  in 
figure  3.  This  is  traversed  by  a  yellowish,  obliquely-banded,  serpentine 
vein,  while  the  adjacent  bordering  serpentine  is  filled  with  the  ferruginous 
products  rejected  during  the  process  of  the  formation  of  the  serpentine  vein. 
Plate  VII.  figure  2  shows  a  peridotite  in  which  the  change  has  gone  so  far 
that  no  trace  remains  of  the  original  structure,  while  the  precipitated  ferru- 
ginous products  largely  assume  the  form  of  a  rectangular  grating  in  the 
yellow  serpentine. 

In  figure  3  of  the  same  plate,  is  shown  an  altered  Iherzolite  in  which 
enstatite  forms  the  groundwork,  inclosing  the  olivine.  The  enstatite  shows 
the  usual  greenish  alteration  along  the  cleavage  planes  and  throughout  much 
of  the  interstitial  portions.  The  olivine  is  chiefly  distinguished  by  the 
rejection  of  large  quantities  of  magnetite  dust  on  the  borders  of  the  grains 
and  their  fissures.  Sometimes  the  separation  of  the  ferruginous  material 
in  this  form  has  been  carried  so  far  as  to  render  the  olivine  grains  nearly 
or  quite  opaque.  Figure  4  shows  a  further  change  in  this  Iherzolite,  in 
which  the  enstatite  is  partly  replaced  by  greenish  serpentinous  material,  and 
partly  by  dolomite  and  other  secondary  products.  The  olivine  is  altered 
and  in  part  replaced  by  serpentine,  magnetite,  etc.,  although  portions  yet 
remain  unchanged.  Figure  5  indicates  a  still  further  alteration  in  this 
Iherzolite,  and  one  in  which  the  enstatite  and  part  of  the  olivine  have  been 
replaced  by  a  groundmass  of  granular  dolomite.  The  olivine  grains  now 
appear  only  in  the  greenish  and  brownish  pseudomorphs  after  that  mineral, 
inclosed  in  the  dolomite  groundmass.  Figure  6  shows  a  yellowish  secondary 
serpentine  mass  with  inclosed  colorless  grains  of  unaltered  olivine,  and,  so 
far  as  this  portion  of  the  section  is  concerned,  is  closely  like  that  shown  in 
Plate  IV.  figure  4,  except  in  the  former  the  serpentine  is  yellow,  and  in  the 
latter  it  is  green.  But  in  addition,  there  occur  in  the  serpentine,  in  the 
above-mentioned  figure  G,  gray  and  brownish  particles  and  grains  of  secon- 


172  PEKIDOTITE. 

dary  dolomite  that  evidently  have  replaced  a  portion  of  the  groundmass,  and 
in  other  parts  of  the  section  have  produced  an  ophicalcite. 

An  interesting  series  of  llierzolites  is  shown  in  the  first  five  figures  of 
Plate  VIII.  In  figure  1  is  represented  a  groundmass  of  enstatite  enclosing 
fissured  and  unaltered  olivine  grains  holding  picotite.  The  pyroxene  mineral 
is  but  slightly  changed,  showing  this  in  one  greenish  band  —  extending  a 
little  distance  from  one  of  the  upper  olivines  —  also  in  the  yellowish-brown 
tinge  of  the  whole  mass.  We  next  pass  into  a  form  (fig.  2)  in  which  the 
pyroxene  minerals  are  more  changed  and  of  a  deeper  brownish  color,  while 
the  boundaries  between  them  and  the  olivine  are  less  distinct.  Again,  the 
separation  of  the  iron  ore-dust  along  the  fissures  and  borders  of  the  olivines 
becomes  strongly  marked,  and  a  series  of  black  ore-bands  extends  across  the 
lower  portion  of  the  sectioa  In  figure  3  the  alteration  is  seen  to  be  still 
greater,  the  color  of  the  pyroxenes  higher,  and  their  cleavage  planes  nearly 
obliterated  ;  while  in  some  cases  a  bluish  border  extends  between  them  and 
the  olivine  grains.  The  olivines  are  much  altered  to  a  greenish  serpentine, 
showing  its  network  formation  along  the  fissures,  and  with  the  iron  ores 
holding  in  the  interstices  some  still  unaltered  portions  of  olivine.  However, 
in  some  of  the  grains  the  whole  mass  has  been  replaced  by  serpentine. 
Here,  as  elsewhere,  it  can  be  seen  that  while  iron  ores  are  the  first  pro- 
ducts formed  during  the  progress  of  the  chemical  changes  which  lead  to 
the  production  of  serpentine,  these  ores  either  disappear  during  the  sub- 
sequent changes,  or  else  are  aggregated  together  in  collections  of  greater 
or  less  size. 

Figure  4  shows  a  still  further  progress  in  the  alteration,  the  pyroxenes 
being  greatly  changed  and  in  some  parts  replaced  by  a  grayish  mineral,  as 
shown  on  the  left  of  the  centre.  Only  a  very  few  portions  of  the  olivine 
have  escaped  the  general  alteration  to  a  yellowish  serpentine,  while  the 
original  fissures  of  the  olivine  are  shown  by  the  arrangement  of  the 
remnants  of  the  ore  bands.  In  figure  5  the  alteration  of  the  rock  has 
progressed  still  further,  the  pyroxenes  being  entirely  changed  or  nearly  so ; 
and  the  olivine  completely  altered  to  a  pale  yellowish  serpentine,  in  which 
only  portions  of  the  ore-bands  are  still  visible. 

This  series  of  sections  possesses  an  additional  interest  from  its  bearings 
on  the  eozotin  question,  for  they  were  examined  by  Dr.  Wm.  B.  Carpenter,  in 
the  presence  of  Mr.  Alexander  Agassiz  and  myself,  regarding  the  occurrence 
of  eozoon  in  them.  They  belong  to  the  variety  of  peridotite  commonly 


ITS   MICROSCOPIC   CHARACTERS  173 

called  schillerfels,  and  are  usually  looked  upon  as  being  of  eruptive  origin. 
It  c.-in  be  readily  seen  that  the  present  writer  regards  the  series  as  forming 
a  progressive  set  of  changes,  coming  down  in  regular  order  from  the  first  to 
the  fifth;  but  Dr.  Carpenter  took  a  different  view.  He  Tdund  the  remains 
of  co-noil  in  every  one,  but  the  fossil  was  best  preserved  in  the  last  section 
(fig.  5),  and  it  was  more  and  more  illy  defined  in  regular  order,  through 
nu'tainorphic  action,  following  the  retrograde  arrangement,  going  from 
figure  5  back  to  figure  1. 

The  same  ground  was  also  taken  by  Dr.  Carpenter  in  reference  to  the 
sections  shown  in  figures  5,  4,  and  3,  of  Plate  VII.,  although  field  evidence 
has  shown  this  rock  to  be  of  eruptive  origin.*  EozoQn  in  various  stages 
of  preservation  was  found  by  him  in  other  sections,  even  including  some 
made  from  dolomitic  veinstones.  Sections  of  the  felsite  pebbles  forming  the 
Calumet  and  Hecla  conglomerate,  and  other  bands  of  conglomerate  on 
Keweenaw  Point,  were  shown  Dr.  Carpenter.  The  present  writer  in  1880  t 
called  attention  to  the  simulative  appearance  of  organic  structure  assumed 
by  their  groundmass  during  the  alteration  of  the  rocks.  On  examining  these 
sections,  Dr.  Carpenter  thought  that  the  rocks  must  be  of  organic  origin,  and 
these  forms  the  remains  of  sponges  and  other  protozoa.  Now  it  is  to  be 
remembered  that  the  original  source  of  these  pebbles  has  been  found  by 
Foster  and  Whitney,  \  and  later  by  Irving,  §  in  eruptive  felsites  breaking 
through  the  copper-bearing  rocks. 

In  the  examinations  made  by  Dr.  Carpenter  of  the  various  sections  laid 
before  him,  it  was  noticed  that  the  more  the  rock  was  altered,  or  the  nearer 
it,  approached  a  veinstone  in  character  —  or  better,  when  it  was  a  veinstone 
—  the  more  perfect  and  the  better  preserved  were  the  fossils. 

Dr.  Carpenter  was  frankly  told  the  writer's  views  about  the  eozoVn,  the 
origin  of  the  rocks  in  question  so  far  as  known,  the  supposed  mode  of 
production  of  these  forms,  and  the  object  of  their  presentation  to  him ; 
and  he  as  frankly  and  unreservedly  gave  his  opinions.  Of  course,  since  Dr. 
Carpenter's  views  have  not  been  published  over  his  own  name,  and  were  not 
the  fruits  of  long-continued  critical  study  on  the  specimens  in  question, 
they  are  not  proper  subjects  for  criticism  —  as  his  published  views  would  be. 
The  object  for  presenting  them  here,  is  simply  to  call  attention  to  the  fact 

•  A*te,  pp.  136-139  ;  also  Bull.  Mus.  Comp.  Zoiil.,  1880,  VIL  60-6G. 

f  Bull  Mus.  Comp.  Zool.,  1880,  VII.  113-120. 

J  Geology  of  Lake  Superior,  Copper  Lauds,  1850,  pp.  70,  71. 

§  Sec.  Ann.  Rep.  Director  U.  S.  Geol.  Survey,  1881,  p.  33. 


174  PERIDOT1TE. 

that  zoologists  and  palaeontologists,  however  skilled  they  may  be  in  the 
study  of  organized  remains,  tend  to  extend  that  kingdom  in  which  they 
have  most  experience  over  every  form  of  the  mineral  world  simulating 
organic  forms.  So,  too,  it  is  not  to  be  denied,  on  the  other  hand,  that 
mineralogists  and  lithologists  are  likewise  prone  to  unduly  extend  their 
kingdom.  In  all  such  cases  of  dispute,  between  the  biologists  on  one  hand 
and  the  petrographers  on  the  other,  every  effort  should  be  made  to  show 
that  the  conditions  under  which  the  rock  containing  the  supposed  organic 
remains  was  formed,  were  incompatible  with  one  or  the  other  view,  instead 
of  leaving  the  question  to  the  weight  of  aiithority.  For  example,  while  the 
lithologist  might  insist  for  all  time  that  these  forms  were  produced  by 
alteration,  and  that  he  could  trace  every  step  from  the  beginning  to  the  end, 
the  biologist  might  also  insist  that  the  forms  were  organic,  and  that  he  could 
trace  every  step  from  the  most  perfect  form  to  those  whose  structure  had 
been  almost  entirely  obliterated  by  subsequent  metamorphism.  Both  follow 
the  same  series,  but  each  one  traces  it  out  in  the  reverse  way  from  the  other. 
Who  shall  decide  between  them  ?  Plainly  this  can  only  be  done  satisfactorily 
by  independent  evidence  which  will  disprove  one  side  or  the  other.  For 
example,  the  mode  of  occurrence  of  some  of  the  rocks  in  which  Dr. 
Carpenter  found  fossils,  is  that  of  eruptive  bodies  and  veinstones ;  therefore, 
the  proof  of  their  origin  decides  the  question,  in  these  cases,  adversely  to 
the  biologist. 

The  case  of  the  eosoon  affords  another  example  of  the  successful  appli- 
cation of  the  above  method  of  determining  the  nature  of  a  disputed  form. 
It  has  been  found  by  Professor  Whitney  and  myself  that  limestone  contain- 
ing eozoon,  acknowledged  to  be  such  by  Carpenter,  Dawson,  and  Hunt,  cuts 
off  dikes  running  through  the  country  rock ;  thereby  proving  this  eozoonal 
limestone  to  be  a  later  deposit  than  the  country  rock,  or  a  veinstone.  This 
decides  the  case  completely  against  the  biologist,  and  removes  from  the 
decision  every  element  of  ambiguity  or  theoretical  reasoning ;  since  a  vein- 
stone formation  of  later  date  than  the  country  rock  is  entirely  incompatible 
with  the  growth  of  an  organism  such  as  the  eosoon  is  claimed  to  be.* 

In  figure  6,  Plate  VIII.,  is  shown  one  of  the  picrites  in  which  the  augite 
appears  on  the  right  hand  of  the  section.  This  mineral  exhibits  in  places, 
particularly  at  its  base,  a  greenish  alteration-product,  and  it  incloses  grains 
of  olivine  fissured  and  partly  altered  to  serpentine.  The  remaining  portion 

*  Bull.  Hus.  Comp.  Zool.,  1884,  vii.  528-538. 


ITS   MICROSCOPIC   CHARACTERS.  175 

of  the  section  is  composed  of  serpentine,  olivine,  biotite  plates,  iron 
ores,  etc. 

In  the  course  of  the  conversion  of  peridotites  into  serpentine,  it  has  been 
seen  that  the  original  characters  of  the  rock  were  gradually  obliterated, 
giving  a  texture  to  the  serpentine  that  showed  its  mode  of  formation.  But 
it  was  found  that  on  further  change,  patches  appeared  which  showed  no  trace 
of  the  mode  of  formation,  and  that  these  gradually  occupied  the  entire  rock- 
mass,  yielding  specimens  whose  microscopic  characters  gave  no  clue  to  their 
origin.  In  these  extreme  alterations  a  more  or  less  schistose  structure  is 
often  produced  in  the  rock,  and  from  this,  the  writer  conceives,  has  arisen 
the  view  already  referred  to,  that  serpentine  rocks  are  derived  from 
schists  as  well  as  from  massive  rocks  (ante,  pp.  144-147).  The  absence  of 
the  reticulated  or  mesh  structure  in  the  serpentine,  and  the  supposed  want 
of  chromite  and  picotite  appear  to  be  entirely  due  to  the  great  alteration 
which  produces  a  structure  in  the  rock  almost  if  not  quite  identical  with  that 
of  serpentine  veinstones.  The  only  apparent  difference  between  the  mode  of 
formation  of  these  serpentines  that  are  homogeneous  and  the  serpentine 
veinstones,  appears  to  be  that  in  one  the  molecular  or  chemical  changes  have 
taken  place  in  the  body  of  the  rock,  while  in  the  other  a  transference  to  a 
new  locality  has  been  superadded.  There  may  be  mentioned  amongst  the 
various  products  of  alteration  found  in  the  peridotites  —  besides  serpentine, 
dolomite,  and  iron  ores  —  the  following  :  actinolite,  hornblende,  smaragdite, 
quartz,  zircon,  spinel,  garnet,  feldspar,  talc,  chlorite,  biotite,  and  various 
other  micaceous  minerals  and  carbonates. 

For  the  special  variations  and  further  details,  the  reader  is  referred  to  the 
descriptions  of  the  specimens  from  different  localities.  The  points  that 
seemed  to  the  writer  most  important,  in  the  case  of  nearly  every  peri- 
dotite  or  group  of  peridotites  which  has  been  microscopically  studied,  have 
been  presented  in  the  preceding  pages.  This  was  necessitated  by  the  small 
number  of  Cordilleras  peridotites  at  hand,  and  our  still  imperfect  knowl- 
edge of  the  group,  which  seemed  to  demand  somewhere  a  tolerably  complete 
summary  of  the  observed  cases  and  their  combination  into  a  connected 
series. 


176  PERIDOTITE. 


SECTION  VII.  —  Chromitc  and  Picotile.  —  Their  Relations. 

AN  interesting  question  is  the  relation  of  chromite  to  picotite.  Professor 
H.  Fischer  described  the  former  as  opaque,  yet  sometimes  magnetic  from  the 
contained  magnetite  ;  *  but  in  a  later  paper  he  stated  that  chromite,  in  the 
finest  dust  and  under  a  high  power,  was  translucent  and  of  a  red-brown  to 
red  color.f 

Dr.  E.  Dathe  found  that  the  chromite  from  Baltimore  was,  in  thin  splinters, 
translucent  and  of  a  brown  color  much  like  brown  obsidian  glass,  and  that 
this  phenomenon  could  be  observed  with  a  low  power.  The  same  was  also 
found  by  him  to  be  true  of  the  chromite  from  Waldheim.t  From  this,  Dathe 
concluded  that  the  ordinary  microscopic  distinction  between  picotite  and 
chromite,  based  on  the  translucence  of  the  one  and  the  opaqueness  of  the 
other,  was  incorrect.  M.  J.  Thoulet  also  found  that  the  chromite  from  Roraas 
in  Norway,  and  that  from  Negropont,  were  translucent,  showing  in  trans- 
mitted light  a  color  mixed  with  yellow  and  red.  The  grains  were  traversed 
by  fissures  which  were  impregnated  with  the  surrounding  rock  material, — 
serpentine  in  the  first  case,  calcite  in  the  second.  In  reflected  light  the 
chromite  shows  a  violet-rose  color  or  a  gray,  and  in  the  portions  impregnated 
by  magnetite  the  characteristic  metallic-blue  reflection  of  the  latter  mineral 
was  observed. § 

Although  the  translucency  of  chromite  is  considered  by  lithologists  to 
have  been  first  noticed  by  Fischer,  it  would  appear  to  have  been  earlier 
remarked  by  C.  H.  Pfaff,  who  stated  in  1825,  in  describing  a  compact  mass 
of  chromic  iron  from  Massachusetts,  that  it  was  characterized  by  a  thin  violet 
rim  on  the  plane  of  fracture. || 

In  order  to  ascertain,  so  far  as  possible,  the  microscopic  relations  of 
picotite  to  chromite  and  the  other  iron  ores,  a  number  of  sections  have 
been  re-examined  with  special  reference  to  these  points ;  and  the  powder  of 
picotite  and  chromite  from  a  number  of  different  localities  has  also  been 
microscopically  studied. 

*  Kritiselie  mikroslcopisch-mineralogischc  Studicn,  1869,  pp.  5,  G,  20-22. 
f  Ibid.  1873,  pp.  44,  77. 
J  Ncucs  Jahr.  Min.,  1876,  pp.  247-2 19. 
§  Bull.  Soc.  Min.  Trance,  1879,  ii.  34-37. 

||  "  Charakteristisch  fiir  dieses  Chromeisen  ist  eine  diinne  violette  Rinde  auf  den  Ablosungsflachen.    Die 
Masse  war  derb."  Jour.  Chemie  Physik,  1825,  xlv.  101-103. 


CHROM1TK   AND    PICOTITE.  177 

The  picotitc  from  Vicdessos  is  coffee-brown  to  yellowish-brown,  translu- 
cent, and  shows  a  smooth  surface  in  reflected  light.  The  chromite  or  picotite 
of  St.  Paul's  Rocks  is  greenish-brown  to  brownish-yellow  in  color,  translucent, 
and  contains  in  association  with  it  and  in  its  interior,  grains  of  pyrite  and 
other  iron  ores  of  secondary  origin.  The  chromite  itself  is  here  thought  to 
also  be  an  alteration-product. 

The  mineral  in  the  Todtmoos  peridotite  shows  in  part  a  pale  yellowish 
central  portion  surrounded  and  traversed  by  portions  of  a  coffee-brown  color 
which  fade  into  a  surrounding  black  opaque  exterior.  Number  142  G.,  from 
San  Domingo,  has  its  mineral  in  part  colored  deep  coffee-brown,  translucent, 
and  traversed  by  dark  opaque  bands,  part  of  which  are  magnetite.  The 
mine-nil  is  in  part  entirely  opaque.  In  numbers  3001  and  3002  from  Colusa 
Co.,  California,  the  picotite  or  chromite  is  yellowish-brown  in  part,  but  most 
is  opaque  and  gives  a  dull,  grayish  reflection.  Some  grains  were  found  to  be 
partly  filled  with  pyrite,  and  some  are  traversed  by  black  opaque  bands  along 
the  fissures,  while  others  again  show  a  brownish  surface  in  reflected  light, 
traversed  by  bluish  magnetite  veins.  One  grain  had  a  translucent  centre, 
with  a  brown  opaque  border  cut  by  magnetite  veins. 

The  mineral  in  the  Baste  schillcrfds  is  in  part  coffee-brown  and  in 
part  opaque.  The  translucent  grains  contain  opaque  portions.  In  this, 
as  in  many  of  the  others  examined,  the  opacity  appears  to  arise  from, 
and  to  be  proportionate  to,  the  amount  of  alteration  in  the  picotite  or 
chromite. 

In  the  Webster  (N.  C.)  peridotite  the  smaller  grains  are  coffee-brown  and 
translucent,  but  the  thicker  interior  portions  are  of  a  much  darker  color  than 
the  edges.  The  larger  grains  are  coffee-brown  and  translucent  on  their 
edges,  but  opaque  in  the  interior,  and  show  a  rough  surface  with  a  dull 
reflection.  A  few  of  the  smaller  grains  have  the  same  characters.  The 
powder  is  coffee-brown  and  translucent  on  the  thin  edges.  The  mineral  in 
the  Andestad-See  rock  is  of  a  coffee-brown  color  in  the  thinnest  portions,  and 
in  minute  grains,  but  the  remaining  portions  are  opaque,  and  give  the  usual 
dull  reflection.  Some  of  the  grains  are  cut  by  fissures  filled  with  serpentine. 
Part  of  the  grains  in  the  Tafjord  rock  are  entirely  translucent  and  have 
a  yellowish-brown  to  a  reddish-brown  color  ;  part  are  entirely  opaque,  and 
have  a  rough  surface  with  a  dull  lustre ;  while  part  have  the  exteriors  and 
some  of  the  central  portions  translucent,  and  their  remaining  portions 
opaque.  The  Tron  (Norway)  rock  has  the  centres  of  the  grains  translucent 

23 


178  PERIDOTITE. 

and  of  a  deep  reddish-brown  color.  The  remaining  portions  are  crystalline- 
granular,  with  a  dull  lustre.  The  Texas  (Pa.)  chromite  in  the  sections  is 
mainly  opaque  and  traversed  by  fissures  filled  with  serpentine.  The  surface 
of  the  chromite  is  rough,  crystalline-granular,  and  the  lustre  dull ;  but  in  the 
thinnest  portions  the  mineral  is  translucent  and  of  a  brown  color.  The 
powder  in  the  thin  portions  is  translucent  and  of  a  greenish  and  reddish- 
brown  color.  The  color  of  the  massive  chromite  is  velvety  black,  and  it  has 
a  resinous  to  vitreous  lustre,  like  the  chromite  from  North  Carolina.  The 
mineral  in  the  serpentine  from  Windisch-Matrey  (Tyrol)  is  mostly  opaque 
and  filled  with  magnetite,  but  a  little  of  it  was  seen  to  be  translucent  and  of 
a  brownish  color.  The  mineral  in  the  Franklin  (N.  C.)  peridotite  is  entirely 
opaque  in  the  thin  section,  and  its  surface  shows  a  dull  lustre,  is  black,  rough, 
and  granulated ;  but  its  powder  is  translucent  and  of  a  deep  yellowish-brown 
color  on  the  thin  edges. 

The  ores  in  the  Herborn  (Nassau)  picrite  are  all  opaque.  Part  have  a 
bluish  reflection,  and  part  a  dull  one.  The  grains  are  in  part  mixed  with 
pyrite.  A  brownish  translucence  seen  at  the  borders  of  the  ores  in  a  few 
cases,  is  here  considered  to  be  owing  to  the  coloration  of  the  adjacent 
silicates  by  the  iron  oxides. 

In  the  peridotites  (mostly  serpentines)  from  Gj^rud  and  Christiania, 
Norway;  Elba;  Presque  Isle  and  Ishpeming,  Michigan;  Westfield  and 
Lynnfield,  Massachusetts  ;  High  Bridge,  New  Jersey  ;  Newport,  Vermont ; 
Deadwood,  Hepsidam,  Chip  Flat,  and  Depot  Hill,  California ;  numbers  120 
G.  and  252  G.,  San  Domingo ;  and  Tasmania,  the  ores  seen  are  all  opaque, 
while  part  are  undoubtedly  magnetite. 

The  general  characters  of  the  chromites  or  picotites  and  other  iron  ores 
in  the  peridotites  of  the  "  Assos  Expedition  "  are  as  follows  :  A.  E.  324  has 
the  centre  of  one  grain  of  a  yellowish-brown  color  with  a  velvety  reflection. 
The  border  is  granular,  opaque,  and  traversed  by  fissures  filled  with  serpen- 
tine. Some  of  the  other  grains  are  reddish-brown,  and  translucent  in  spots ; 
the  remaining  portions  of  these  grains,  and  the  entire  mass  of  the  remaining 
grains  are  opaque. 

A.  E.  265  has  its  chromic  ores  in  grains  and  octahedrons,  which  are  trans- 
lucent and  of  a  deep  brown  color.  They  show  a  brilliant  bluish  lustre  in 
reflected  light. 

A.  E.  207  has  part  of  its  grains  translucent  on  the  thin  edges,  and  of  an 
orange-brown  to  a  deep  cherry-red  color ;  while  the  remaining  grains  are 


CIIROMITE   AND   PICOTITE.  179 

opaque.  Of  part  of  the  grains  the  reflection  is  dull ;  but  of  others,  even  of 
the  translucent  parts,  it  is  bluish  metallic;  structure,  granular. 

Most  of  the  isometric  oxides  in  A.  E.  209  are  opaque  and  in  irregular  gran- 
ules and  crystals.  Some  of  the  larger  grains  are  traversed  by  an  irregular 
network  of  crystalline  grains,  giving  a  bluish  metallic  reflection,  and  holding 
interstitial  portions  of  a  dull  lustre.  Part  of  these  interior  portions  are 
opaque,  and  part  are  translucent  and  of  a  deep  reddish-brown  color. 

In  A.  E.  217,  473,  and  216  two  different  kinds  of  ore  were  observed. 
One  is  granular,  opaque,  and  bluish-black  in  reflected  light.  The  other  is  a 
dull,  earthy-brown,  amorphous  mass  in  reflected  light,  but  translucent  and  of 
a  pale  grayish-brown  color  by  transmitted  light.  The  two  are  frequently 
united  in  the  same  grain,  and  the  first  is  here  considered  to  be  magnetite, 
while  the  second  is  a  limonitic  product  of  decomposition  of  iron  ores. 

A.  E.  481  has  it.s  mineral  in  irregular  opaque  grains  of  a  dull  lustre,  and 
traversed  by  cracks  filled  with  serpentine. 

A.  E.  214,  270,  274,  482,  483,  483  (bis),  484,  485  have  their  ores  all 
opaque  and  granular,  giving  a  bluish  reflection. 

Through  the  kindness  of  Professors  F.  A.  Genth  and  Edward  S.  Dana,  a 
number  of  chromites  were  obtained  for  examination. 

The  following  twenty-four  were  sent  by  Dr.  Genth.  All  were  found  to 
be  translucent,  most  showing  this  with  a  low  power,  but  some  required  a 
high  power.  The  color  is  a  yellowish-brown  in  transmitted  light,  in  the 
specimens  from  Westfield,  Vermont;  Chester,  Massachusetts;  Walter  Green's 
mine,  Delaware  Co.,  Pennsylvania ;  Moro  Phillip's  mine  in  Marple  Township, 
Delaware  Co.,  Pennsylvania;  Webster,  Jackson  Co.,  North  Carolina;  and 
Western  North  Carolina.* 

The  chromite  from  the  Phillips  mine,  Nottingham,  Chester  Co.,  Pennsyl- 
vania, is  of  a  yellowish-brown  color  tinged  variously  with  green  and  reddish- 
brown.  That  from  Media,  Delaware  Co.,  Pennsylvania,  is  in  crystals,  the 
powder  of  one  of  which  is  perfectly  opaque,  and  that  of  another  a  deep 
yellowish-brown.  In  the  following  the  color  is  a  deep  yellowish-brown  and 
a  reddish-brown :  Davis  Moore's  mine,  Middletown  Township,  Delaware  Co., 
Pennsylvania ;  Wood's  mine,  Texas,  Lancaster  Co.,  Pennsylvania ;  the  Red 
Pit,  and  Low's  mine  from  same  county ;  Soldier's  Delight,  Maryland ;  Culs- 
agee,t  Macon  Co.,  North  Carolina ;  Hampton's,  Yancy  Co.,  North  Carolina ; 

*  This  last  is  from  the  specimen  analyzed  by  Dr.  Gentli  as  being  from  Franklin,  Macon  Co.,  North 
Carolina,  and  containing  it. 15  per  cent,  of  chromic  oxide.  (See  table  of  analyses.) 

f  There  were  two  si>ccimcus  from  this  locality,  one  in  octahedral  crystals,  the  other  massive. 


180  PERIDOTITE. 

Troup  Co.,  Georgia ;  Dudleyville,  Alabama ;  California ;  near  New  Idria, 
Monterey  Co.,  California ;  Ural  Mountains ;  and  Euboea,  Greece.  Another 
specimen  from  California  had  a  yellowish  and  greenish-brown  color,  while 
one  from  Sweden,  when  very  thin,  was  of  a  deep-brown  coffee-color. 

The  seven  following  chromites  were  sent  by  Dr.  Dana.  Those  from 
Lancaster  Co.,  Pennsylvania ;  Cecil  Co.,  Maryland ;  Franklin,  North  Carolina ; 
and  Bisersk,  Ural  Mountains,  have  a  yellowish-brown  color.  Two  specimens 
from  Texas,  Pennsylvania,  require  to  be  very  thin  to  become  translucent, 
and  are  of  a  yellowish-brown  to  reddish-brown  color.  One  from  Jamaica, 
West  Indies,  is  greenish-yellow  in  its  apparently  freshest  state,  but  in  the 
partially  changed  condition  it  is  reddish-brown. 

A  chromite  obtained  from  Mr.  Kerr,  Commissioner  from  North  Carolina 
at  the  New  England  Fair  of  1883,  in  thin  splinters  is  of  a  clear  coffee-brown 
color  with  a  greenish  tinge.  Its  fracture  is  smooth,  and  presents  a  surface 
closely  resembling  a  hardened  black  gum  or  pitch  —  for  example,  albertite  — 
and  has  a  lustre  varying  from  resinous  to  vitreous.  This  was  chipped  from 
a  large  block  sent  to  that  exhibition.  Most  of  the  chromites  examined  have 
a  pitchy  or  resinous  look,  with  a  velvet-black  color  closely  resembling  solid 
coal  tar ;  but  some  are  dull.  While  it  may  be  said  that  in  general  more  or 
less  translucency  exists  in  the  powder  of  chromite,  this  apparently  resides 
only  in  certain  portions  of  the  mineral,  which  is  not  translucent  as  a 
whole. 

So  far  as  the  writer  is  aware,  no  tests  have  been  made  to  compare  the 
relative  hardness  of  picotite  and  chromite,  but  the  former  has  been  assumed 
to  have  that  of  the  normal  spinel.  In  the  same  way  the  color  of  the  streak 
of  picotite  does  not  appear  to  be  known  for  itself  ;  while  that  of  chromite 
would  seem  to  be  due  to  its  translucency. 

In  specific  gravity  the  two  minerals  bear  close  relations.  Chromite  varies 
in  its  specific  gravity  as  follows:  4.031,  4.0639,  4.11,  4.115,  4.1647,  4.319, 
4.422,  4.439,  4.49,  4.50,  4.534,  4.56,  4.566,  and  4.568;  while  the  only  deter- 
mination of  picotite  found,  places  it  at  4.08. 

Both  minerals  have  the  same  crystallographic  form,  the  same  color  to  their 
thin  sections,  and  the  same  color  and  lustre  in  the  massive  state. 

The  term  cofcc-brown  as  used  in  this  text  and  in  the  writings  of  others 
partakes  of  the  same  variability  in  shade  that  the  infusion  of  coffee  itself  does, 
running  from  a  yellowish  or  greenish-brown  through  a  reddish-brown  to  a 
deep  dirty-  or  muddy-brown.  The  depth  of  color,  even  in  the  same  specimen, 


AND   PICOTITE.  181 

appears  to  be  due  in  part  to  the  thickness,  and  in  part  to  alteration.  For 
example,  in  some  the  yellowish-brown  and  reddish-brown  shades  are  mingled 
in  such  a  manner  that  it  is  evident  that  the  latter  shade  is  due  to  change  in 
the  state  of  the  iron,  and  marks  a  stage  in  the  progression  towards  opacity. 
In  other  cases  the  two  tints  are  so  related  that  the  shade  is  seen  to  be  due 
to  the  wedge-shaped  form  of  the  fragment  examined. 

The  translucency  is  better  observed  in  the  powder  than  in  the  thin  sec- 
tion, il'  the  mineral  tends  to  be  at  all  opaque,  since  thinner  edges  are  obtained 
by  the  process  of  fracture.  The  writer  has  found  the  quickest  and  simplest 
w;i  v  to  prepare  the  powder  for  microscopic  examination,  —  to  place  a  minute 
fragment,  less  than  a  pin's  head  in  size,  on  a  glass  slide,*  and  then  crush  it  on 
this  slide  under  a  clean  knife-blade.  The  scattering  of  the  powder  can  be  pre- 
vented by  placing  a  finger  over  the  blade  at  the  point  under  which  the  grain 
lies.  In  this  way,  by  using  a  small  blade,  the  finger  projects  over  both  sides 
and  serves  as  a  cushion  to  prevent  the  broken  particles  from  flying  off,  gives 
a  more  uniform  pressure,  and  saves  the  production  of  so  much  fine  dust  as  to 
obscure  our  observations.  Thus  the  powder  can  be  directly  examined  on  the 
slide  on  which  it  was  crushed. 

It  does  not  appear  practicable  at  the  present  time  to  enter  upon  any 
satisfactory  discussion  of  the  chemical  relations  existing  between  picotite  and 
chromite  ;  yet,  as  a  contribution  towards  that  desired  end,  a  list  of  analyses 
of  the  two  minerals  has  been  arranged  in  order  of  the  relative  percentage 
of  chromic  oxide,  and  it  will  appear  in  the  list  of  tables  as  Table  I.  One  of 
the  difficulties  in  the  way  of  a  satisfactory  determination  of  the  relations 
of  chromite  and  picotite  is  the  absence  of  analyses  made  from  material  care- 
fully studied  microscopically,  as  well  as  a  like  absence  of  analyses  made  from 
material  of  intermediate  grades  between  the  typical  picotite  and  the  typical 
chromite.  For  it  will  not  escape  the  observer's  attention  that  the  analyses 
naturally  group  about  these  two  poles,  since  typical  specimens  arc  selected 
for  analysis.  Another  difficulty  is  the  fact  that  only  five  analyses  of  picotite 
and  one  of  chrompicotite  are  known,  out  of  the  one  hundred  and  twenty 
analyses  here  collected.  Hence  it  is  that  the  series  of  analyses  is  far  from 
being  so  continuous  as  it  would  probably  be  found  to  be  if  more  attention 
had  been  paid  to  the  question  of  the  relations  of  these  two  minerals. 

The  percentage  of  chromic  oxide  begins  as  low  as  4.74  per  cent  in  one 
chromite,  and  in  the  picotites  does  not  rise  higher  than  8  per  cent,  while  the 

*  Any  window-glass,  if  cut  of  proper  size  for  tlie  stage  of  the  microscope,  will  do. 


182 


PERIDOTITE. 


chromites  next  in  order  contain  9.80, 16.80,  three  between  17  and  18  per  cent, 
then  21.16  and  31.20.  The  chrompicotite,  however,  contains  56.54  per  cent 
of  chromic  oxide.  The  highest  percentage  is  77-00,  in  a  doubtful  analysis 
by  C.  H.  Pfaff ;  while  the  next  lower  has  64.17  per  cent. 

The  highest  percentages  of  alumina  in  the  chromites  are  30.17,  27.83,  and 
24.71,  but  in  general  it  diminishes  in  amount  as  the  chromium  increases. 
In  picotite  the  alumina  is  high,  being  50.34,  52.47,  53.93,  55.34,  and  56.00 
per  cent,  and  in  this  occurs  the  only  real  chemical  difference  between  pico- 
tite and  chromite.  In  the  chrompicotite  the  alumina  is  12.13.  The  percent- 
age of  magnesia  is  about  the  same  in  both  the  chromites  and  picotites,  and 
does  not  bear  any  observable  proportion,  to  any  other  element.  The  highest 
percentages  are,  in  picotite  23.59,  and  in  chromite  28.71  and  25.40. 

The  oxides  of  iron  irregularly  increase  as  the  chromic  oxide  does,  rising 
as  high  as  45.22,  48.46,  and  62.02,  while  the  lowest  percentages  are  2.30, 
5.60,  and  9.00;  but  picotite  contains  the  following:  22.27,  21.42,  15.25, 
24.60,  and  24.90,  and  the  chrompicotite  18.01.  The  silica  and  lime  diminish 
irregularly  as  the  chromic  oxide  increases.  The  highest  percentages  of  silica 
are  26.01,  26.70,  and  14.211;  and  of  lime  24.36,  13.26,  and  10.55. 

The  minor  and  rare  elements  are  the  oxides  of  nickel,  manganese,  and 
carbon. 

The  more  general  relations  are  perhaps  best  shown  in  the  tables  inserted 
here  in  the  text. 

TABLE  I. 


No.  of  Analyses. 

23. 

25. 

27. 

28. 

17. 

Limits  of  Cr203 
percentages. 

4.74-38.1',*. 

39.O5-44.91. 

45.00-52.12. 

sa.ia-sr.ao. 

5S.OO-77.00. 

Percentage  Lim- 
its of  Elements. 

t 

o 
K 

S 
o 

J 

I 

_^ 

| 

1 

| 

i 

d 

1 

I 

Si 
I 

: 

I 

! 
s 

-• 

i 

1 

d 

3 

J 

ri 
A 

j 

8 

? 
9 

4 
c 
o 
Z 

~ 
~ 

^ 

s 

i 

i 

* 

S 

Of 

r 

I 

1 

MffO 

1 

J. 

5 

in 
17 
8 

14 
7 
11 
3 

2 

4 
5 
8 
2 
1 

I 

1 

5 
5 
5 

°1 

11 
10 
5 
o 

2 
9 

10 

8 

1 

ii 

n 

15 
2 

•in 

n 

3 
6 
1 

3 

12 
29 

5 

•>\ 
5 

13 
6 
4 
3 

19 

6 

4 

1 

3 
14 

10 

8 

1 
13 
3 

3 
G 
3 

y 

8 

ALO, 

1 
3 

5 

7 

r 

8 

11 

Fc2Oa£FeO 
SiO2 

11 

12 

5 

5 

'i' 
U_ 

0 

CaO 

17 

8 

21 

3 

Table  I.  has  placed  in  its  upper  line  the  number  of  analyses  in  each  set ; 
in  the  second  line,  the  percentage  limits  of  the  chromic  oxide  in  these 
analyses ;  while  on  the  third  line  is  placed  the  percentage  limits  of  the 
magnesium,  aluminum,  ferric,  ferrous,  silicon,  and  calcium  oxides.  Below  are 
given  the  number  of  analyses  found  in  the  above  limits.  Thus,  for  instance, 


CHROMITE   AND   PICOTITE. 


183 


in  looking  at  the  table  it  can  be  seen  that  in  the  first  23  analyses  the  limits 
of  Cr203  are  4.74  and  38.12;  while  in  these  23  analyses,  there  are  to  be 
found  of  analyses  of  Mg  0,  one  having  no  Mg  0  ;  four  having  less  than  10  per 
cent;  fourteen  carrying  between  10  and  20  per  cent;  four  carrying  between 
20  and  30  per  cent ;  and  none  having  any  higher  percentage.  But  in  these 
same  23  analyses  we  see  that  there  are  five  (picotites)  which  carry  between 
50  and  GO  per  cent  of  A12  O8. 

TABLE  II. 


Percentage  I.innt  -. 

t 

a 
o 
S5 

0 

3 

I 

: 

i 

i 

3 

i 

i 

8 

2 

si 

|i 

Cr.O, 

7 

4 

i 

IB 

3f> 

43 

13 

i 

Fe'o!.' 

81 

10 

8 

fi 

10 

1 

FcO 

IS 

4 

98 

49 

18 

5 

a 

ALO,  ...  . 

8 

53 

36 

19, 

1 

5 

4 

MjrO 

15 

49 

55 

8 

SiOj  

17 

<n 

g 

9, 

1 

CaO. 

19 

97 

<& 

1 

In  Table  II.  there  is  given  in  the  upper  line  the  percentage  limits  for  the 
different  constituents,  and  below,  the  number  of  analyses  whose  constituents 
fall  between  those  limits.  Thus  it  will  be  seen  that  out  of  the  120  analyses, 
there  are  seven  containing  less  than  10  per  cent  of  Cr203,  four  between  10 
and  20  per  cent,  etc.;  while  there  are  81  analyses  in  which  no  Fe203  is  re- 
ported and  one  which  has  between  60  and  70  per  cent  of  it.  From  the  above 
illustrations,  the  use  of  the  tables  will  doubtless  be  readily  understood. 

In  reply  to  a  question  of  the  present  writer  as  to  his  views  concerning 
the  chemical  relations  of  chromite  and  picotite,  Dr.  Genth  states  that,  in 
common  with  many  others,  he  thinks  "  that  all  the  aluminates,  ferrates,  etc. 
of  Mg,  Zn,  Mn,  and  Fe,  which  are  isometric,  are  only  varieties  of  the  species 
R  Ra  04  —  which  so  gradually  change  from  one  into  the  other,  that  it  is  often 
difficult  to  say  where  one  begins  and  the  other  ends.  Of  typical  forms  we  have 
only  spinel  (Mg  A1204),  magnetite  (Fe  Fe204),  and  magnoferrite  (MgFe204). 
All  the  rest  are  mixtures.  As  for  chromite,  I  have  never  seen  a  specimen 
which  did  not  contain  magnesia  and  alumina,  although  some  of  the  analyses 
do  not  give  any ;  but  there  are  a  great  many  poor  analyses." 

In  the  same  manner,  Rammelsberg  classes  together  chromite  sind  picotite, 
not  even  placing  the  latter  under  spinel.* 

In  the  microscopic  study  of  chromites  and  picotites  we  see  a  reason  for 
the  variability  in  their  chemical  analyses,  and  the  nearly  constant  presence 
*  Handbuch  der  Miueralcbemie,  1875,  pp.  111-144. 


184  PERIDOTITE. 

of  silica  and  other  impurities.  We  further  find  various  gradations  in 
different  specimens,  and  even  partly  in  the  same  grain,  between  the  yel- 
lowish- to  reddish-brown  mineral,  and  that  which  is  opaque  and  crystalline- 
granular,  with  or  without  magnetite  or  some  of  the  other  iron  ores,  like 
limonite  or  hematite. 

The  above  investigations  apparently  point  to  the  following  conclu- 
sions :  — 

That  picotite  iu  its  freshest  state  is,  in  the  thin  sections,  a  yellowish-  or 
greenish-brown,  clear  mineral  which  is  subject  to  alterations,  causing  the 
color  to  deepen  to  a  darker  brown  or  muddy  coffee-color,  and  even  to  a 
black  and  opaque  mass.  The  changed  forms  vary  from  a  dull,  earthy  mass 
to  a  crystalline-granular  one  which  frequently  contains  more  or  less  magne- 
tite. Commonly,  the  more  the  rock  is  altered  or  changed  to  a  serpentine, 
the  less  apt  is  one  to  find  any  of  the  translucent  grains,  and  the  greater  is 
the  amount  of  magnetite. 

It  is  probable  that  picotite  and  chromite  belong  to  the  same  mineral 
series,  the  term  picotite  being  more  commonly  applied  to  the  freshest  states, 
and  that  of  chromite  to  those  forms  more  altered,  and  to  the  local  aggrega- 
tions arising  from  the  migration  of  the  chromic  oxide  during  the  alteration 
of  the  associated  peridotic  rock. 

The  results  deduced  from  the  microscopic  study  of  minerals,  lead  to  the 
conclusion  that  most  of  our  mineral  species  are  not  definite  compounds 
corresponding  to  a  special  chemical  formula,  but  rather  are  varying  and 
variable  compounds.  They  are  seen  to  contain  inclusions  of  various  kinds, 
and  to  exist  in  various  stages  of  alteration  and  decomposition.  This  we  see 
in  the  case  of  micaceous  products  which  occur  in  certain  greenish,  fibrous, 
and  scaly  forms,  produced  from  the  alteration  of  various  minerals.  Now, 
while  these  forms  are  microscopically  undistinguishable  from  one  another  in 
their  earlier  stages,  they  are  seen  to  result  in  their  further  change,  in  the 
production  of  biotite,  hornblende,  chlorite,  hydrous  micas,  etc.  Now  shall  we 
give  a  distinct  name  to  each  of  these  variable  and  interminable  micaceous 
forms,  whenever  from  its  analysis  we  can  torture  a  chemical  formula  into 
being ;  or  shall  we  recognize  the  variability,  and  use  our  mineral  names 
simply  as  type-names  about  which  the  related  products  in  their  various 
stages  are  grouped  ?  The  latter  is  the  method  employed  in  this  work.  The 
variability  of  mineral  species  not  only  occurs  in  the  micaceous  minerals  above 
mentioned,  but  it  is  seen  in  picotite  and  the  ores  of  iron,  the  feldspars,  serpen- 


CHROMITE   AND   PICOTITE.  185 

tino,  pyroxenes,  aniphiboles,  and  in  almost  every  mineral  or  group  of  minerals 
that  has  been  studied  to  a  sufficient  extent  to  afford  us  much  information 
about  its  composition.  Our  minerals  in  Nature's  laboratory  appear  to  be 
produced  and  grow,  to  change  and  decay,  to  pass  away  and  be  succeeded  by 
others,  ever  passing  onward  from  the  unstable  towards  the  more  stable  ;  re- 
action after  reaction,  replacement  after  replacement,  following  one  another 
according  to  the  varying  conditions,  as  they  do  in  the  chemist's  laboratory. 
When  we  can  learn  the  order  of  succession  by  alteration,  and  the  various 
relations  minerals  thus  hold  to  one  another,  we  may  hope  for  a  natural  sys- 
tem of  mineralogy,  which  will  display  to  us  their  origin  and  line  of  descent, 
with  their  relationships.  In  the  establishment  of  such  a  system,  the  micro- 
scope and  chemical  reagents  must  go  hand  in  hand,  and  the  work  is  yet 
hardly  begun. 

An  analysis  of  a  chromite  from  Eoraas,  Norway,  given  in  Table  I.,  Las  had 
a  strange  history.  Jt  was  attributed  to  Laugier  by  Rammelsbcrg  in  his 
Handworterbuch  des  chemischen  Theils  der  Mineralogie,  1841,  pp.  163,  164, 
and  in  his  Handbuch  der  Mineralchemie,  1860,  pp.  171-174;  and  from  these 
works  of  Rammelsberg  it  has  been  copied  in  the  third,  fourth,  and  fifth 
editions  of  Dana's  System  of  Mineralogy,  and  elsewhere.  The  work  from 
which  the  analysis  is  said  to  have  been  takep  is  the  sixth  volume  of  the  Ann. 
Mus.  d'Hist.  Nat.  It  was  proved  by  the  present  writer  not  to  occur  there, 
and  after  a  long  search,  its  history  has  been  found  to  be  as  follows  :  — 

The  analysis  was  published  in  the  Annales  des  Mines,  1829  (2),  V.  316, 
as  taken  from  the  "  An.  du  Bureau  des  mines  de  Suede,  t.  9,  1825,"  but  the 
name  of  the  analyst  was  not  given.  Since  the  writer  is  unable  to  see,  for 
the  present  at  least,  the  Swedish  journal  referred  to,  the  analysis  has  not 
been  traced  any  further  backwards.  It  was  then  copied  by  Beudant,* 
together  with  an  analysis  of  Seybert,  but  in  both  cases  without  mention  of 
the  analyst  or  the  source.  Before  this,  however,  it  had  been  republished  by 
Franz  von  Kobell,t  without  being  attributed  to  any  analyst,  and  without 
reference  to  the  original  source,  but  placed  after  a  reference  to  an  analysis 
by  Laugier.  This  then  evidently  gave  rise  to  Ramrnelsberg's  mistake  ;  while 
it  also  led  Hausmann  t  and  Brooke-and-Miller§  to  attribute  the  analysis  to  Von 
Kobell  himself,  as  they  have  done  in  their  mineralogies.  Thus  this  analysis 


ir  I'lrmentaire  de  Mineralogie,  1S32,  ii.  607,  GG8. 
f  Clianiktrristik  der  Mineralien,  Kil,  ii.  255. 
f  Handbuoli  dor  Miiicrnluu-ic,  IS  17.  ii.  420. 

§  AJI  Elementary  Introduction  to  Mineralogy,  by  the  late  William  Phillips,  1852,  p.  203. 

24 


186  PERIDOTITE. 

has  been  credited  over  forty  years  to  a  chemist  by  whom  it  showed  on  its  face 
it  could  not  have  been  made,  since  Laugier  was  not  in  the  habit  of  carrying 
his  percentages  into  the  decimals,  at  most,  beyond  one  place. 

This,  and  numerous  other  mistakes  which  have  been  found  in  the  process 
of  looking  up  the  analyses  for  this  work,  are  obviously  due  to  the  neglect  of 
authors  to  verify  the  analyses  which  they  take  at  second  hand.  The  present 
writer  has  no  doubt  that  he  has  contributed  his  quota  of  errors  also,  although 
he  has  endeavored  to  go  to  the  fountain-head  when  possible ;  but  with  the 
accidents  of  twice  copying  and  of  passing  the  work  through  the  press,  the 
chance  for  errors  to  creep  in  are  great ;  and  they  could  only  be  entirely 
eliminated  by  again  searching  out  the  scattered  literature,  and  comparing 
the  originals  with  the  tables  in  type  —  a  labor  which  is  impracticable  at  the 
present  time. 

SECTION  VIII.  —  Peridotite.  —  Its  Chemical  Characters. 

IN  the  appended  table  of  chemical  analyses  (Table  IV.),  when  the  variety 
to  which  the  meteorite  belongs  is  known,  the  name  of  the  variety  is  given, 
with  an  asterisk  prefixed  to  indicate  that  it  is  a  meteorite.  When  the  variety 
is  unknown,  the  simple  designation,  meteorite,  is  employed.  The  varieties  of 
the  terrestrial  peridotites  are  given  so  far  as  possible ;  but  when  not  known, 
the  term  used  by  the  analyst  to  designate  the  rock  is  placed  in  the  column 
of  varieties. 

The  specific  gravity  of  the  unaltered  peridotites  is  generally  between 
3.00  and  3.80,  with  the  meteorites  standing,  as  a  whole,  somewhat  higher 
than  the  terrestrial  forms,  since  they  are  less  altered.  As  the  alteration 
proceeds,  the  percentages  in  general  fall,  as  was  observed  in  the  case  of 
cumberlandite.  Two  of  the  carbonaceous  meteorites  fall  very  low  on  the 
scale,  being  1.7025  and  1.94.  These  meteorites  are  thought  to  belong  to 
this  group  in  all  respects  except  their  carbonaceous  matter,  for  sections  of 
the  Cold-Bokkeveld  meteorite  are  seen  as  dense  black  masses,  with  brownish- 
gray  spots  of  silicates  and  carbonaceous  grains.  The  whole  mass  is  very 
friable,  and  the  silicates  are  in  minute  grains ;  but  they  appear  to  be  chiefly, 
if  not  entirely,  olivine  and  enstatite.  The  resemblance  to  a  mass  of  mixed 
soot  and  olivine  grains  is  striking  —  the  latter  being  seen  scattered  here  and 
there  through  the  dark  mass. 

To  return :    the  specific    gravity  of  the    altered    forms,  particularly  of 


ITS   CHEMICAL  CHARACTERS.  187 

serpentine,  lie  almost  entirely  between  2.50  and  3.00.  This  decrease  in 
specific  gravity  is  generally  accompanied  with  a  diminution  of  the  relative 
ferruginous  contents,  and  an  increase  in  that  of  the  magnesia. 

It  was  observed  in  the  pallasites  that  only  one  contained  over  30  per  cent 
of  silica,  while  it  may  be  seen  here  that  only  three  of  the  Iherzolites  fall 
below  that  percentage,  and  one  of  these  is  a  carbonaceous  meteorite  which 
contains  considerable  organic  matter  and  water.  Another  of  these  analyses 
is  considered  to  be  worthless.  In  the  mention  of  the  chemical  analyses, 
reference,  as  a  rule,  is  had  to  the  first  one  when  more  than  one  is  given  for  a 
single  locality ;  for  when  several  analyses  are  available,  that  one  is  placed 
first  which  is  thought  to  be  the  more  nearly  correct,  judging  by  the  analyses 
and  the  analyst,  when  any  especial  difference  exists.  Of  course,  no  such 
differences  in  composition  occur  in  the  same  specimen,  as  some  of  the  given 
analyses  display,  and  many  of  these  are  poor  and  unreliable. 

Only  two  of  the  analyses  show  for  peridotite  a  higher  percentage  than 
47  per  cent  —  St.  Paul's  Rocks  47.15,  and  the  Cabarras  meteorite  56.168. 
This  meteorite  has  in  general  been  assigned  to  the  basaltic  division  of  the 
meteorites ;  but  since,  macroscopically,  it  has  the  characters  of  the  peridotites, 
it  has  here  been  placed  with  them,  in  the  belief  that  some  error  exists  in  the 
published  analysis.  It  is  to  be  hoped  that  a  microscopic  examination  and 
further  chemical  analyses  will  be  made  of  the  Cabarras  stone. 

Only  two  meteoric  and  three  terrestrial  peridotites  have  a  percentage  of 
silica  above  45,  and  below  47,  per  cent.  One  of  the  meteorites  has  two 
analyses  in  which  the  silica  is  respectively  46  and  48.25  per  cent,  made  by 
Higgins  in  1811.  Had  the  second  analysis  been  placed  first,  then  the  above 
statements  would  have  varied  accordingly. 

From  the  above  it  can  be  seen  that  out  of  193  different  peridotites 
analyzed,  all  but  11  have  their  percentage  of  silica  lying  between  30  and  45, 
while  the  vast  majority  are  included  between  33  and  43  per  cent.  The 
meteorites  preponderate  in  the  lower  percentages  —  the  terrestrial  rocks  in 
the  higher  ones. 

Except  in  the  case  of  the  picrites  there  cannot  at  present  be  said  to  be 
any  gradation  in  the  percentages  of  silica,  according  to  the  variety,  from 
dunite  up  to  picrite,  although  a  tendency  towards  some  arrangement  has 
been  observed.  Of  course,  the  more  nearly  the  rock  approaches  to  a  purely 
olivine  one  or  to  a  pure  serpentine,  the  more  nearly  the  percentage  of  silica 
will  correspond  to  the  typical  analyses  of  those  minerals. 


188  PERIDOTITE. 

The  vast  majority  of  analyses  show  a  percentage  of  alumina  less  than  5, 
but  the  picrites  tend  to  have  more  (mostly  between  10  and  20),  as  also  some 
of  the  others,  thus  approaching  the  basalts.  The  highest  percentage  is  in  the 
Muddor  stone  analyzed  by  Frank  Crook  —  26  percent  —  a  doubtful  analysis. 

The  amount  of  iron  in  various  states  distinctly  varies  in  the  meteoric  and 
terrestrial  peridotites ;  so  much  so,  that  from  the  sum  of  the  percentages  the 
class  can  readily  be  inferred  in  most  cases.  In  the  meteorites  the  iron  in 
every  condition  varies  somewhere  about  the  mean  of  30  per  cent  —  those 
forms  having  the  lower  percentages  of  silica,  usually  more  than  30,  and 
those  having  the  higher  percentages  of  silica,  contain  generally  less  than  30 
per  cent. 

In  the  terrestrial  peridotites  the  iron  percentages  are  commonly  below  10, 
and  universally  below  20  per  cent  The  more  highly  altered  the  rock,  the 
less  is  the  percentage  of  iron.  This  agrees  with  the  microscopic  observations, 
and  shows  that  in  the  process  of  alteration  much  iron  is  removed  and  stored 
up  elsewhere. 

Lime  is  either  absent  in  the  peridotites,  or  less  than  5  per  cent  in  the  vast 
majority.  The  cases  in  which  higher  percentages  are  found  are  apparently 
due  to  incorrect  analyses,  or,  in  the  main,  to  the  picrites  and  two  serpentines 
which  are  associated  with  gabbro,  and  may  possibly  be  altered  forms  of  it  — 
a  conclusion  to  which  their  relatively  high  contents  of  alumina  and  lime 
point.  The  picrites  show  their  near  relation  to  the  basalts  in  the  same  way. 
19.50  per  cent  of  lime  (the  highest)  was  found  in  the  typical  Iherzolite  from 
Vicdessos,  in  an  analysis  published  in  1813.  It  is  thought  that  here  the  lime 
and  magnesia  were  poorly  separated,  or  else  the  peridotite  has  been  in  some 
way  modified  by  the  limestone  through  which  it  was  erupted!  No  other 
peridotite  contains  over  13.61  per  cent  of  lime. 

The  magnesia  percentage  is  relatively  high  but  variable,  and  it  tends  in 
the  meteorites  and  picrites  to  lie  below  30  per  cent,  and  in  the  other  perido- 
tites to  be  above  that.  Of  course,  the  nearer  the  rock  comes  to  being  a  pure 
olivine  one,  or  to  be  entirely  altered  to  serpentine,  the  more  nearly  the 
percentages  correspond  to  the  typical  ones  for  those  minerals.  Part  of  the 
variability  in  the  percentage  of  magnesia  is  undoubtedly  owing  to  poor 
analyses. 

Chromium,  nickel,  and  cobalt  are  quite  commonly  present,  as  are  al.so 
phosphorus  and  sulphur  in  the  meteoric  forms.  Sometimes  copper  and  tin 
are  found.  The  more  highly  altered  the  peridotites,  the  more  apt  is  water 


ITS   ORIGIN.  189 

to  be  present,  and  in  the  serpentine  rocks  it  appears  in  general  to  vary  from 
8  to  16  per  cent. 

In  general,  the  peridotites  are  relatively  low  in  their  percentages  of  silica, 
alumina,  and  lime;  high  in  magnesia;  and  variable  in  iron  and  specific 
gravity ;  the  unaltered  forms  being  higher,  in  both  cases,  than  the  altered. 


SECTION  IX.  —  Peridolite.  —  Its  Origin. 

"Are  the  peridotites  sedimentary  or  eruptive  ?  "  is  an  exceedingly  impor- 
tant question,  and  one  which,  in  the  case  of  serpentine,  has  been  frequently 
argued. 

That  the  peridotites  are  sometimes  eruptive,  the  cases  cited  by  Bonney, 
Diller,  and  the  present  writer,  for  Cornwall,  the  Troad,  and  Lake  Superior, 
are  clear,  explicit,  and  decisive  —  that  they  occur  in  dikes,  in  intrusive 
tongues,  and  in  uplifting,  altering,  eruptive  bosses,  showing  the  same  char- 
acters as  do  other  eruptive  rocks,  especially  those  of  a  coarse-grained  charac- 
ter like  gabbro  and  granite.  That  the  peridotites  are  in  part  eruptive  we 
should,  then,  consider  a  settled  fact ;  but  another  case  still  remains  to  be 
considered :  the  association  of  these  rocks  with  schists. 

Where  schistose  rocks  are  associated  with  the  peridotites,  especially  the 
serpentine  variety,  their  relations  would  appear  to  be  accounted  for  in  the 
following  ways :  — 

1.  They  may  occur  as  eruptive  rocks  which,  with  their  associated  country 
rocks,  have  later  been  altered,  producing  a  general  apparent  blending  of  all 
into  a  single  series ;  as  it  is  well  known  has  taken  place  with  the  older  erup- 
tive basaltic  rocks  —  diorite,  diabase,  melaphyr  —  which  has  caused   them 
also  to  be  looked  upon  as  interbedded  sedimentary  rocks,  in  common  with 
their  associated  schists. 

2.  All  may  have  come  from  the  alteration  of  eruptive  material,  —  the  len- 
ticular patches  being  the  remnants  of  the  altered  rock.     This  would  be  in 
accordance  with  the  well-known  mode  of  alteration  of  olivine  rocks,  in  which 
occur  clear  grains  of  unaltered  olivine  surrounded  by  the  serpentine  and 
other  secondary  minerals  which  often  give  to  the  rock  a  schistose  character. 
We  might  as  well  claim  that  these  clear  olivine  grains  were  produced  by  the 
metamorphosis  of  the  serpentine  and  schistose  material,  when  the  reverse  is 
known  to  be  the  case,  as  to  claim  that  the  patches  of  olivine  rocks  in  schists 


190  PEEIDOTITE. 

were  produced  by  the  metamorphosis  of  the  schistose  material,  when  the 
reverse  is  probably  true. 

3.  All  other  eruptive  rocks  are  subjected  to  denudation,  and  their  debris 
piled  up  somewhere  with  other  associated  sedimentary  beds ;  hence  there  is 
every  reason  to  believe  that  we  have  detrital  peridotitic  rocks,  the  same  as 
we  have  detrital  basaltic  ones. 

All  three  of  the  preceding  methods  are  probably  correct  for  some  cases, 
but  which  method  is  to  be  advocated  in  each  case  is  to  be  determined  by  the 
study  of  the  locality  in  question. 

Although  as  yet  it  does  not  seem  to  be  proved  that  peridotic  volcanoes 
have  existed,  and  peridotic  ash  may  not  have  been  formed,  we  should  look 
for  all  the  intermingling  of  the  eruptive  peridotic  material  with  its  own  debris 
and  with  that  of  other  rocks,  the  same  as  previously  set  forth  in  general 
terms  for  rocks  of  this  origin  (ante,  pp.  22-24).  We  should  then  expect  to 
find  the  peridotites  occurring  in  dikes  and  eruptive  masses,  in  altered  schis- 
tose or  foliated  rocks,  in  detrital  beds,  and  in  every  form  and  every  associa- 
tion that  it  is  possible  for  eruptive  rocks  and  their  debris  to  exist  in.  The 
study  of  these  occurrences  would,  however,  be  expected  to  be  just  so  much 
more  obscure  than  is  the  study  of  the  basaltic  rocks,  as  the  former  are  more 
basic  and  easily  alterable  than  the  latter. 

That  serpentines  are  produced  from  the  alteration  of  peridotic  rocks,  is 
the  testimony  of  all  lithologists  who  have  studied  their  structure  with  the 
microscope,  and  it  is  one  of  the  most  fixed  facts  in  the  science.  That  serpen- 
tines are  not  produced  in  other  ways  may  perhaps  be  looked  upon  as  an  open 
question  at  the  present  time,  although  there  would  seem  to  be  no  proof  of 
any  other  mode  of  origin.  In  the  case  of  any  mineral  formed  by  secondary 
changes,  more  or  less  migration  of  the  mineral  material  is  apt  to  occur, 
and  in  this  way  the  secondary  serpentine  is  frequently  found  in  veins, 
and  in  other  localities  outside  of  the  rock  from  whose  alteration  it  was 
produced. 

That  serpentines  have  come  from  chemical  precipitates  from  ocean  waters, 
is  a  view  which  certainly  does  not  appear  to  have  any  proof  in  its  behalf,  and 
one  which  probably  arose  from  the  confounding  of  veinstone-serpentine  or 
migrated  serpentine  material,  with  that  produced  by  the  alteration  of  perido- 
tites in  situ.  The  production  of  serpentine  by  the  alteration  of  olivine  and 
its  removal  and  storage  in  fissures  arid  adjacent  rocks,  brings  in  connection 
with  the  peridotites  the  difficult  problems  belonging  both  to  eruptive  rocks 


ITS  ORIGIN.  191 

and  veinstones ;  and  the  phenomena  of  both  would  appear  to  explain  the 
mysteries  hovering  about  the  serpentine  question. 

The  writer  has  been  unable  to  find  anything  in  the  published  reports  of 
the  Canada  Geological  Survey  to  substantiate  the  often  repeated  statement, 
that  this  survey  had  proved,  prior  to  1858,  that  the  Canadian  serpentines 
were  in  stratified  sedimentary  deposits.  The  geologists  of  that  survey  appear 
to  have  assumed,  without  proof,  that  the  serpentines  were  so  deposited,  and 
worked  out  their  geology  on  that  supposition.  Then,  finally  forgetting  the 
basis  on  which  the  assumed  stratification  was  placed,  they  afterwards  declared 
that  they  had  proved  these  rocks  to  be  stratified ;  but  the  correctness  of  that 
statement  is  not  here  allowed.  And  in  this  connection  it  may  be  said  that 
Dr.  Hunt's  "  Geological  History  of  the  Serpentines  "  is  looked  upon  here  as 
having  the  same  inaccuracies  that  all  his  other  papers  have  been  found  to 
contain,  when  the  present  writer  has  had  occasion  to  critically  examine  their 
contained  statements,  both  of  fact  and  opinion  (ante,  p.  38).* 

The  question  now  arises :  Can  serpentine  result  from  the  alteration  of  any 
rock  except  the  peridotites  ?  In  the  preceding  pages  it  has  been  shown  that 
olivine  is  the  chief  producer  of  serpentine,  but  that  in  olivine  rocks  enstatite 
and  even  diallage  are  changed  to  serpentine,  although  more  slowly  than  the 
olivine.  It  has  also  been  shown  that  in  the  cumberlandite  more  or  less 
serpentine  had  been  formed  during  the  alteration  of  this  olivine-magnetite 
rock.  So,  too,  it  is  well  known  to  lithologists  that  the  olivine  of  the  basaltic 
rocks  is  subject  to  alteration  to  serpentine,  whic'h,  in  the  gabbros  and  other 
old  basalts,  produces  a  rock  imperfectly  serpentinous.  It  would  seem,  then, 
that  any  rock  containing  olivine  or  enstatite,  may  become  more  or  less  ser- 
pentinized,  although  it  would  appear  that,  outside  of  the  peridotites  proper, 
true  serpentines  that  are  not  veinstones,  rarety,  if  ever,  occur. 

The  reader  is  further  referred,  for  the  literature  and  general  discussions 
of  the  serpentine  question  by  others,  to  Roth's  "  Ueber  den  Serpentin  und 
die  genetischen  Beziehungen  desselben,"  t  Riess's  "  Ueber  die  Entstehung 
des  Serpentins,"  \  and  the  lithological  text-books  of  Rosenbusch  and 
Zirkel. 

The  production  of  talcose  rocks  or  talcose  schists,  as  early  advocated  by 
Genth  (ante,  p.  119)  appears  to  be  one  of  the  results  of  the  alteration  of 

•  See  also  "  Azoic  System,"  Bull.  Mus.  Comp.  Zool.,  1S84,  vii.  No.  11 ;  and  Bonney,  Geol.  Mag.,  1884  (3), 
i.  400-412. 

t  Abli.  Berlin.  Akad.,  18f>9,  ii.  329-361. 

J  ZciU  Gessam.  Katur.  Berlin,  1879  (3),  iv.  1-18. 


192  PERIDOT1TE. 

peridotites,  especially  those  containing  pyroxene  minerals ;  but  the  present 
writer's  studies  would  indicate  to  hirn  that  the  most  common  source  that 
yields  by  alteration  our  soapstone  or  steatite  rocks,  is  to  be  sought  in  our 
gabbros  and  coarser  crystalline  diabases  (diorites).  The  purer  talcose  rocks 
would  appear  to  come  from  the  former  source  (the  peridotites),  the  more 
impure  ones  from  the  latter  (the  basalts). 

From  the  evidence  in  the  preceding  pages,  it  is  probable  that  some  actino- 
litic  and  other  schists  result  from  the  alteration  of  the  peridotites,  although 
in  general  the  amphibole  schists  appear  to  belong  to  other  groups. 

The  formation  of  impure  dolomites  from  peridotites  would  seem  to  have 
been  clearly  shown  in  the  preceding  pages,  but  how  far  this  will  account  for 
the  common  association  of  magnesian  limestones  with  serpentine,  is  a  problem 
for  the  future.  One  thing,  however,  appears  clear,  that  such  limestones  are 
produced  on  a  small  scale,  and  sometimes  on  a  more  extended  one  in  connec- 
tion with  the  general  alteration  of  peridotites  into  serpentine. 

It  is  not  the  part  or  intention  of  the  writer  to  explain  the  modes  of 
change  in  these  rocks.  It  is  rather  his  part  to  give  the  facts  observed,  and 
for  the  mineral  chemist  to  engage  in  the  work  of  explanation,  unless  he  can 
impeach  the  facts  presented. 


SECTION  X.  —  PcridoUte.  —  Its  Classification. 

As  previously  stated  (ante,  pp.  84,  85),  all  rocks  of  this  class  are  here 
grouped  under  one  species  or  type — peridotite ;  while  for  the  modifications 
produced  by  the  variation  in  mineral  composition,  varietal  names  are  em- 
ployed, in  deference  to  the  views  of  those  who  make  species  out  of  every 
mineral  variation  in  rocks.  Since,  so  far  as  practicable,  these  variety  names 
are  the  same  as  the  specific  names  of  other  lithologists,  and  have  the  same 
general  limits,  no  difficulty  will  arise  in  their  use,  whether  the  person  em- 
ploying them  looks  upon  each  division  as  a  specific  or  a  varietal  term. 

In  accordance  with  the  methods  of  this  work,  peridotite  is  defined  as 
including  all  meteoric  and  terrestrial  rocks  of  every  age,  which  are  composed 
essentially  of  olivine,  with  or  without  pyroxene  minerals,  and  iron  ores 
including  picotite. 

It  has  not  been  customary  to  base  any  varietal  distinction  on  the  iron 
ores,  or  hardly  to  look  upon  them  as  essential,  although  they  are  universally 


ITS  CLASSIFICATION.  193 

present,  or  nearly  so.  The  varietal  distinctions  (specific,  of  other  lithologists) 
are  founded  on  the  pyroxene  minerals  and  on  the  alteration-products.  Thus 
dm, ilc  is  the  terra  given  to  the  form  of  peridotite  which  is  essentially  com- 
posed of  olivine  ;  saronite  to  that  composed  of  olivine  and  enstatite ;  Ihcrzolite 
to  that  composed  of  olivine,  enstatite,  and  diallage ;  hichncrile  to  that  com- 
posed of  olivine,  enstatite,  and  augite  :  cnlysitc  to  that  composed  of  olivine 
and  diallage ;  and  /i/r/-/fe  to  that  composed  of  olivine  and  augite. 

Under  these  varieties  are  classed  all  the  forms  produced  by  alteration,  so 
far  as  they  may  retain  sufficient  original  characters  for  their  identification ; 
when  they  do  not,  then  they  are  placed  under  a  variety  name  belonging  to 
the  produced  form.  Thus,  serpentine  is  given  as  the  variety  name  for  all  the 
altered  peridotites  in  which  serpentine  forms  the  essential  constituent;  talc 
schid  to  all  in  which  talc  holds  a  similar  part ;  and  in  the  same  way  any 
variety  produced  by  alteration  can  be  designated  by  its  common  name  when 
its  derivation  is  known. 

It  is,  however,  expected  that  future  studies  will  lead  to  the  discovery 
of  every  mineralogical  combination  that  can  be  formed  by  the  principal 
silicate  constituents  of  peridotite.  These  combinations,  so  far  as  now 
known  grade  into  one  another,  and  it  is  to  be  expected  that  all  other  dis- 
covered ones  will  do  the  same.  Hence,  if  the  ordinary  methods  of  nomen- 
clature should  be  followed,  the  number  of  species  or  varieties  of  peridotite 
would  be  great  and  their  separation  difficult.  However,  the  present  writer, 
as  he  has  previously  stated,  does  not  place  any  stress  upon  the  subdivisions 
now  made  on  a  mineralogical  basis  in  peridotite,  but  adopts  them  as  a  con- 
venience only  in  the  present  state  of  lithological  science  ;  and  they  can 
readily  be  replaced  by  the  general  employment  of  the  specific  name  — 
perulolili'. 

The  limburgite  of  Rosenbusch  has  not  been  placed  here  with  the  peridotites, 
for  its  microscopic  structure  is  like  that  of  some  of  the  porphyritic  glassy 
basalts,  and  differs  much  from  the  peridotites.  While  its  percentage  of  silica 
is  like  that  of  this  species,  its  contents  of  alumina  and  lime  ally  it  to  a  more 
acidic  group;  although  it  is  not  improbable  that  it  belongs  to  the  picrite 
variety.  Except  in  its  abundant  olivine,  limburgite  microscopically  closely 
approaches  some  of  the  andesites ;  but,  taking  its  characters  as  a  whole, 
the  majority  of  them  appear  to  be  basaltic,  and  with  that  group  it  will  here 
be  classed  until  further  evidence  can  be  procured. 

The  fragmental  states  of  the  peridotites  arc  indicated  for  the  unaltered 

25 


194 


PEEIDOTITE. 


and  altered  forms  by  the  respective  varietal  terms,  tufa  and  porodite,  or,  if 
desirable,  their  adjective  forms,  tvfaccous  and  poroditic. 

Below  is  given  a  table  showing  the  classification  of  all  the  rocks  more 
basic  than  the  basalts,  so  far  as  now  known,  but  it  admits  of  the  ready  addi- 
tion of  other  varietal  names,  and  even  of  specific  ones,  if  future  studies  shall 
indicate  such  divisions.  The  three  designated  classes  of  varieties  are  of  course 
not  entirely  distinct,  since  in  alteration  a  mineralogical  change  enters,  and 
that  change  or  alteration  is  the  basis  of  the  two  divisions  of  the  fragmental 
forms,  while  these  may  partake  of  the  mineral  characters  of  the  mineralogi- 
cal varieties,  and  belong  to  them. 

Table  showing  the  Classification  of  the  Rock  Species  preceding  the  Basalts. 


Species. 

Mineralogical  varieties. 

Alteration  varieties. 

Fragmental  vari- 
eties. 

Siderolite. 

Pallasite. 

Pallasite 
Cumberlandite. 

Actinolite  Schist. 

Dunite. 

Peridotite. 

Saxonice. 
Lherzolite. 
Buchnerite. 
Eulysite. 
Picrite. 

Serpentine. 
Talc  Schist. 
Actinolite  Schist. 

Tufa. 
Porodite. 

This  seeming  confusion  or  crossing  of  names  is  due  to  the  present  state  of 
lithology,  and  the  necessity  of  bringing  the  nomenclature  into  accordance  with 
the  general  usage  and  prejudices  of  lithologists,  since  an  abrupt  departure 
from  their  nomenclature  would  only  repel,  and  the  inconsistencies  can  later  be 
remedied  by  the  dropping  of  all  varietal  names  which  the  advance  of  the 
science  shall  render  superfluous,  as  the  writer  now  believes  many  of  them  to 
be.  Thus,  for  instance,  it  is  here  considered  that  in  peridotite,  the  terms 
peridotite,  serpentine,  and  talc  and  actinolite  schist,  with  the  adjectives  tvfaccous 
and  poroditic,  will  express  every  essential  form  of  these  rocks  now  known, 
and  by  their  use  alone  a  proper  conception  of  their  relations  would  be  ad- 
vanced. 


CHAPTER    IV. 

THE   BASALTS. 

SECTION  I.  —  The  Meteoric  Basalts. 
VARIETY.  —  Basalt. 

Slaimcrn,  Moravia. 

TSCHERMAK  has  described  the  Stannern  meteorite  as  a  gramilar  rock,  showing  an 
evident  fragmental  structure.  According  to  him,  it  is  not  a  homogeneous  crystalline 
rock,  but  oue  composed  of  rock  fragments  of  three  different  kinds :  coarse-grained  frag- 
ments, radiated  finer-grained  fragments,  and  compact  fragments. 

The  coarser-grained  fragments  are  chiefly  composed  of  anorthite  laminae  and  augite 
columns  united  together.  Some  of  the  anorthite  crystals  show  very  fine  twinning,  but 
most  have  broad  twin  laminae  which  are  sometimes  bent.  Besides  the  colorless  anorthite, 
and  the  brown  to  blackish  augite,  Tschermak  observed  a  colorless  isotropic  mineral,  which 
i*  probably  the  same  as  the  mineral  he  had  described  as  an  isotropic  labradorite  (maske- 
lynite)  from  the  Shergotty  meteorite.  Minute  grains  of  chromite,  iron,  and  pyrrhotite 
occur  inclosed  between  the  other  minerals ;  and  black  forms  were  seen  in  the  augite. 

The  fragments,  of  an  evidently  radiated  texture,  are  composed  of  anorthite  laminae 
interspersed  with  augite  needles.  Black  grains  occur  in  these  fragments. 

The  compact  fragments  formed  a  gray  mass,  which  in  several  points  showed  a  radiated 
fibrous  structure,  and  which  contained  the  before-mentioned  black  grains. 

The  groundmass  which  unites  these  fragments  is  composed  of  anorthite  and  augite 
grains,  and  black  particles.* 

Tschermak  later  stated  that  this  meteorite  was  closely  like  that  from  Juvenas,  but  finer- 
grained  ;  but  it  did  not  contain  either  the  unknown  silicate  or  pyrrhotite  found  in  thatf 

The  specimens  of  this  rock  in  the  Harvard  College  Mineral  Cabinet,  resemble  in 
structure,  on  macroscopic  examination,  some  diabases,  but  are  of  a  much  finer  grain ; 
the  general  crystalline  arrangement  is  the  same. 

Constantinople,  Turkey. 

The  Constantinople  meteorite  was  found  by  Tschermak  to  be  an  ash-gray,  nearly 
compact  rock,  composed  of  compact  small  fragments  and  fine  radiating  masses. 

It  was  seen  under  the  microscope  to  be  composed  of  anorthite,  pryoxene,  pyrrhotite, 
and  cliromite.  Its  microscopic  structure  agrees  with  the  Stannern  meteorite,  as  also  does 
its  chemical  composition.^ 

*  Min.  Mitth.,  1872,  pp.  83-85.  f  Die  mikros.  Bescli.  dcr  Meteoriten,  1883,  i.  7. 

J  Min.  Mitth.,  1872,  pp.  85-87.' 


196  BASALT. 

Jbnsac,  France. 

The  Jonzac  meteorite  is  stated  by  Tschermak  to  have  a  fragments!  structure,  and 
under  the  microscope  is  seen  to  be  composed  of  lamella}  of  anorthite  and  columns  of 
augite.  The  former  has  distinct  bounding  lines,  while  those  of  the  augite  are  indistinct. 
Lying  between  these  crystals  are  small  grains  of  the  same  minerals,  filling  the  interspaces. 
The  anorthite  is  often  cloudy  from  minute  brown  glass  inclusions,  and  black  grains  arran- 
ged parallel  to  the  length  of  the  crystal.  The  augite  when  clear  has  a  greenish-brown 
color,  but  it  is  often  traversed  by  fissures,  and  rich  in  violet-blue,  and  brown,  dust-like 
particles,  —  chromite  and  pyrrhotite,  possibly.  The  meteorite  further  contains  pyrrhotite, 
chromite,  and  iron.* 

Petersburg,  Lincoln  Co.,  Tennessee. 

The  Petersburg  meteorite  is,  according  to  Professor  Shepard,  of  an  "  ash-gray  color,  with 
a  slight  intermixture  of  pearl-gray,  for  the  basis  of  the  stone."  Porphyritically  inclosed 
in  this  groundmass  are  crystals  and  grains,  which,  from  Shepard's  and  Smith's  descrip- 
tions, appear  to  be  augite,  plagioclase,  and  olivine.  Some  chromite  and  a  garnet  were 
reported. f 

Tschermak  states  that  it  is  composed  of  anorthite,  augite,  and  a  yellowish  silicate  like 
olivine.J 

The  specimen  in  the  Harvard  College  Cabinet  macroscopically  closely  resembles  the 
Stannern  meteorite. 

Frankfort,  Franklin  Co.,  Alabama. 

The  Erankfort  meteoric  stone,  according  to  Professor  Brush,  presented  a  gray  ground- 
mass  with  a  pseudo-porphyritic  structure,  having  black,  green,  white,  and  dark-gray  spots 
on  it.  Professor  Brush  determined  the  minerals  as  follows  :  the  black  one  as  chromite ; 
the  white  as  anorthite  or  chladnite  (it  is  more  probably  feldspar  than  enstatite) ;  the 
green  and  gray  as  olivine  (probably  some  augite  also) ;  and,  in  addition,  a  little  nickel- 
iferous  iron,  and  pyrrhotite  (troilite).  This  rock  seems  to  be  a  basalt,  to  which  its  chemical 
analysis  refers  it.§ 

VARIETY.  —  Gabbro. 

LuotolaJcs,  Finland,  Rusida. 

The  meteorite  from  Luotolaks  was  found  by  Professor  F.  J.  Wiik  to  be  composed  of 
metallic  iron;  colorless  anorthite;  grayish-violet  augite,  inclosing  long  black  microlites ;  and 
olivine,  with  little  irregular  cavities.||  He  refers  this  meteorite  to  the  basic  eruptives. 

Tschermak  describes  it  as  a  tufaceous  mass,  which,  in  an  earthy,  friable,  gray  ground- 
mass,  holds  splinters  and  grains  of  greenish,  whitish,  and  dark  color,  as  well  as  basaltic 
(eucritic)  fragments.  He  looks  upon  it  as  a  volcanic  ash.  It  contains,  according  to  him, 
anorthite  holding  little  rounded  glass  inclusions ;  augite  in  brownish  grains,  with  black 
needle-formed  inclusions ;  bronzite  in  very  pale,  greenish  splinters,  almost  free  from 
inclusions ;  olivine,  chromite,  pyrrhotite,  and  iron.  ^[ 

*  Min.  Mitth.,  1874,  pp.  163,  109. 

f  Am.  Jour.  Sci.,  1857  (2),  xxiv.  134-137;  Safford's  Geol.  Reconn.  of  Term.,  1856,  pp.  125-127; 
Geol.  of  Tenn.,  1S69,  pp.  520,  521. 

|  Min.  Mitth.,  1874,  p.  170.  §  Am.  Jour.  Sci.,  1869  (2),  xlviii.  240-244. 

||  Neues  Jahr.  Min.,  1883,  i.  384;  Ofvorsigt  Pinska  Vet.  Soc.  Forh.,  1882,  xxiv.  63,  64. 
^f  Die  mikros.  Beseh.  der  Meteoriteii,  1883,  i.  7,  8. 


THE   METEORIC   BASALTS.  —  GABBEO.  197 

Massing,  Bavaria. 

The  Massing  meteorite  is  said  by  Professor  C.  W.  Giimbel  to  be  of  a  grayish-white 
color  in  the  interior,  and  to  contain  olivine  in  yellowish-green  to  clear-green,  round,  and 
irregular  grains,  which  sometimes  show  parallel  fissuring. 

He  refers  to  feldspar  a  white,  glassy,  transparent,  or  dusty,  cloudy,  strongly-fissured, 
rarely  parallel-striped,  evidently  cleavable  mineral.  A  wine-yellow  to  grayish-green,  or 
pale,  reddish-brown  glassy  mineral  is  regarded  as  belonging  to  the  augite  group.  It  is  not 
dichroic,  and  is  sometimes  in  long  fibrous  forms,  and  filled  with  numerous  little  bubbles. 
Besides  these,  chromite,  pyrrhotite,  and  iron  were  found.  All  these  are  cemented  by  a  fine, 
dust-like,  granular,  gray  groundtnass.* 

Tschermak  states  that  the  Massing  meteorite  is  similar  in  character  to  that  from 
Luotolaks,  and  contains  anorthite,  brownish,  yellowish,  and  greenish-gray  augite,  bronzite, 
chromite,  pyrrhotite,  and  greenish  splinters  of  olivine.f 

Jitvcnas,  ArdecJie,  Frame. 

According  to  Eammelsberg,  this  meteorite  is  composed  of  anorthite,  augite,  chromite, 
pyrrhotite,  and  possibly  a  little  apatite,  and  titanite.  It  is  similar  to  the  Stannern  form, 
but  coarser  \  Hose  states  that  the  nickeliferous  iron  is  in  a  very  minute  quantity. § 

The  specimen  in  the  Harvard  College  Cabinet  looks  macroscopically  more  like  a 
gabbro  than  the  Stannern  form,  and  it  has  a  coarser  texture. 

This  meteorite  is  figured  by  Fouque  and  LeVy,  as  being  composed  of  anorthite,  enstatite, 
augite,  and  magnetite,||  and  having  a  structure  like  some  norites. 

Tschermak  states  that  it  shows  a  crystalline  to  tufaceous  structure  under  the  micro- 
scope, and  is  evidently  of  a  brecciated  character. 

The  anorthite  in  it  is  well-crystallized,  part  being  water-clear,  and  part  cloudy  and 
•white,  owing  to  rounded  and  fine  needle-formed  glass  and  other  inclusions  arranged 
parallel  to  the  bounding  planes.  The  crystals  often  show  in  polarized  light  a  compli- 
cated twinning.  Some  of  the  inclusions  hold  bubbles  and  black  grains.  Earely  gas- 
pores  were  seen. 

The  augite  is  brownish-black,  owing  to  numerous  black,  and  rarely  brown,  needle- 
shaped  and  rounded  inclusions.  The  brownish  rounded  inclusions  are  regarded  as  glass. 
Some  irregular  grains  of  a  pale-brown  color  are  referred  to  diallage.  A  pale-brownish 
silicate,  sometimes  having  a  fine  lamellar  structure  was  observed.  Small  amounts  of 
pyrrhotite  and  nickeliferous  iron  were  also  found  by  Tschermak.lT 

Sliergotty,  India. 

A  description  of  the  microscopic  characters  of  the  Shergotty  meteorite  was  given  by 
Professor  Tschermak  in  1872.  The  stone  is  granular,  with  the  grains  nearly  of  the 
same  size,  and  on  the  fractured  surface  it  has  a  yellowish-gray  color.  In  the  thin  section 
five  different  minerals  were  recognized  :  1,  a  brownish  cleavable  mineral  similar  to  augite  ; 
2,  a  glass-clear  isotropic  mineral ;  3,  a  yellowish,  anisotropic  mineral,  very  rare ;  4,  an 
opaque  black  mineral  —  magnetite ;  5,  an  opaque  metallic  yellow  mineral,  extremely  rare. 

•  Sitz.  Miinchcn  Akad.,  1878,  viii.  32-40.  f  Die  mikros.  Besch.  der  Meteoriten,  1883,  i.  8. 

J  Ann.  I'hvsik  flicmio,  1848,  Ixxiii.  5S5-590  ;  1851,  Ixxxiii.  591-593. 

§  AMi.  Berlin.  Akad.  1863,  pp.  120- 134.  ||  Min.  Microfj.,  1879,  plate  LV.  figure  1. 

f  Die  mikros.  Besch.  der  Meteoriteu,  1883,  i.  6,  7;  Min.  Mitth.,  1874,  pp.  169,  170. 


198  BASALT. 

Of  these  the  first  formed  the  principal  portion  of  the  stone.  It  is  traversed  by  number- 
less fine  fissures  parallel  to  the  cleavage.  It  is  of  a  grayish-brown  color,  anisotropic,  and 
shows  only  feeble  pleochroisin.  In  cleavage  and  optical  characters  it  is  similar  to  diopside. 
It  is  quite  commonly  twinned.  While  the  mineral  is  regarded  as  augitic,  Tschermak 
thinks,  from  its  chemical  composition,  that  it  is  different  from  any  terrestrial  compound. 

The  second  mineral  possesses  conchoidal  fracture,  and  is  inclosed  in  and  subordinate  to 
the  augitic  mineral.  Its  form  is  that  of  a  distorted  cube.  The  hardness  is  a  little  less 
than  that  of  orthoclase,  while  its  chemical  composition  is  similar  to  that  of  labradorite. 
Tschermak  proposed  for  it  the  name  maskelynite.  The  third  mineral  is  intergrown  witli 
the  first,  is  traversed  by  parallel  fissures,  and  is  orthorhombic  in  crystallization.  It  is 
referred  to  bronzite  (eustatite). 

The  fourth  mineral  lies  between  the  other  minerals  or  is  inclosed  in  the  maskelynite. 
It  is  pitch-black,  semi-metallic,  with  a  conchoidal  fracture,  black  streak,  and  is  strongly 
magnetic.  This  mineral  is  regarded  as  magnetite.  The  fifth  mineral  is  referred  to 
pyrrhotite.  The  section  as  figured  by  Tschermak  resembles  some  of  the  gabbros.* 

Later,  Tschermak  speaks  of  the  brownish  mineral  as  augite,  and  of  the  inaskelynite  as 
a  glassy  state  of  plagioclase.f 

PaivlowJca,  Saratow,  Russia. 

This  meteorite  has  been  described  by  Mr.  Th.  Tschernyschow,  as  composed  of  a 
brittle  ash-gray  groundmass,  formed  by  a  crystalline-granular  mixture  of  feldspar,  ensta- 
tite,  and  diallage,  holding  porphyritic  grains  of  these  minerals  and  olivine.  The  feldspar 
shows  polysynthetic  twinning,  and  is  referred  to  anorthite.  It  is  in  irregular  and  ledge- 
formed  masses.  The  diallage  is  either  colorless  or  brownish-gray,  with  cleavage  planes, 
and  an  absence  of  dichroism.  The  enstatite  shows  a  fine  parallel  cleavage  striation,  and 
holds  chromite  (?)  in  black  grains  arranged  parallel  to  the  cleavage  lines.  Sometimes  the 
feldspar  predominates,  and  at  others  the  pyroxenes ;  and  of  the  latter,  sometimes  the 
enstatite  and  sometimes  the  diallage  is  most  abundant. 

The  olivine  occurs  in  clear-green  grains.  Besides  the  above  minerals,  there  were  seen 
also  nickeliferous  iron,  pyrrhotite,  and  chromite,  in  grains  and  crystals.  It  also  contains 
the  cloudy-gray  friction-product  of  Tschermak,  but  which  the  present  writer  regards  as  a 
base.  $ 

This  meteorite  is  placed,  from  the  above  description,  with  the  basaltic  meteorites, 
although  the  entire  correctness  of  the  microscopic  diagnosis  is  perhaps  questionable. 

Le  Teilleul,  Manche,  France. 

This  meteorite,  according  to  Daubree,  is  composed  of  plagioclase  (anorthite),  enstatite, 
diallage,  olivine,  iron,  pyrrhotite,  and  chromite. 

The  feldspar  is  colorless,  twinned,  and  presents  similar  inclusions  to  those  found  in  the 
feldspar  of  gabbro.  On  chemical  tests  the  feldspar  is  referred  to  anorthite.  The  enstatite 
shows  two  cleavages,  is  of  a  pale-greenish  color,  and  contains  opaque  inclusions.  The 
diallage  is  of  a  darker  color  than  the  enstatite,  and  contains  inclusions  of  oxide  of  iron  or 
troilite,  as  well  as  other  forms  similar  to  those  common  in  diallage,  and  arranged  parallel 
to  one  another.  The  oliviue  is  colorless.  § 

*  Sitz.  Wicn.  Akml.,  1S72,  Ixv.  (1),  122-135;  Miu.  Mitth.,  1872,  pp.  87-05. 

•j-  Die  mikros.  Besch.  der  Meteoriten,  1883,  i.  7. 

j  Zeit.  Deut.  geol.  Gesells.,  1883,  xxxv.  100-192. 

§  Cumplea  llendus,  1S79,  kxxviii.  544-547;  Neues  Jahr.  Mia.,  1879,  pp.  905,  906. 


THE  METEORIC   BASALTS.  —  GABBRO. 


199 


BukopviBe,  South  Carolina. 

The  meteorite  which  fell  at  Bishopville,  South  Carolina,  March,  1843,  has  been  regarded 
as  an  interesting  and  peculiar  one.  Professor  C.  U.  Shepard,  hi  1846,*  described  from  it, 
iiinler  the  name  of  Cldadnite,  a  mineral  which  he  regarded  as  a  ter-silicate  of  magnesia, 
and  as  forming  over  two-thirds  of  the  stone.  The  color  is  snow-white,  rarely  tinged  with 
gray.  Lustre  pearly  to  vitreous,  translucent,  H.  6-6.5.  Sp.  Gr.  3.116.  Fuses  without 
diiliculty  before  the  blowpipe  to  a  white  enamel.  He  further  describes  as  apatoid,  small, 
yellow,  semi-transparent  grains  having  a  hardness  of  5.5,  and  very  rare.  A  third  mineral, 
which  he  names  iodolite,  is  of  a  pale,  smalt-blue  color,  vitreous  lustre,  and  brittle.  Hard- 
ness 5.5—6.  Fuses  easily  with  boiling  into  a  blebby,  colorless  glass.  The  iodolite  was 
found  only  in  a  small  quantity. 

Later,  Shepard  gave  a  fuller  account  of  this  stone,  holding  that  it  contained,  chladnite 
90  per  cent,  anorthite  6  per  cent,  nickeliferous  iron  2  per  cent,  and  2  per  cent  of  mag- 
netic pyrites,  schreibersite,  sulphur,  iodolite,  and  apatoid.  f 

The  stone  was  next  investigated  by  \V.  Sartorius  von  Waltershausen.  He  described 
the  principal  mass  as  a  white  siliceous  mineral,  forming  a  finely  crystalline  mass,  with 
here  and  there  little  points  showing  metallic  lustre,  also  grains  of  magnetite  and  brown 
oxide  of  iron.  The  hardness  of  the  white  mineral  is  given  as  6,  and  the  specific  gravity 
as  3.039.  His  results  indicated  that  the  siliceous  portion  of  the  meteorite  Was  composed 
of  95.011  per  cent  of  chladnite,  and  4.985  per  cent  of  labradorite.  The  former  he  found 
to  be  monoclinic,  and  related  to  wollastonite  in  specific  gravity,  color,  texture,  hardness, 
and  crystalline  form.  J  Later,  Professor  J.  Lawrence  Smith  stated  that,  from  some  of  his 
investigations,  "  chladnite  is  likely  to  prove  a  pyroxene ; "  §  and  subsequently  published  a 
further  discussion,  in  which  he  said  of  chladnite :  "  It  is  identical  in  composition  with 
Enstatite  of  Kenngott."  ||  Earlier  than  Smith's  last  paper,  some  investigations  were 
made  upon  this  meteorite  by  Professors  Carl  Rammelsberg  and  Gustav  Hose.  The 
former  held  that  the  yellowish-brown  and  bluish-gray  particles  (the  apatoid  and  iodolite 
of  Shepard)  arose  from  the  oxidation  of  the  nickeliferous  iron  or  the  alteration  of  the 
pyrrhotite. 

Hose's  examination  showed  that  the  chladnite  fused  before  the  blowpipe  only  on  the 
the  edges  to  a  white  enamel.  ^[  Eammelsberg,  in  the  continuation  of  bis  work,  further 
declared  that  no  feldspar  was  to  be  found  in  the  stone.**  Through  the  courtesy  of  Mr. 
John  Cummings  and  Professor  A.  Hyatt,  the  Curator  of  the  Boston  Society  of  Natural 
History,  I  have  been  permitted  to  make  a  microscopic  examination  of  a  small  portion  of 
this  meteorite  now  deposited  in  the  collection  of  that  society. 

The  portion  examined  is  a  grayish-white  mass,  resembling,  as  Shepard  remarked, 
a  grayish-white  granite  (albitic),  with  brown  and  black  spots. 

Under  the  microscope  it  is  seen  to  be  composed  of  an  entirely  crystalline  mass  of 
enstatite,  augite,  feldspar,  olivine,  pyrrhotite,  and  iron. 

The  structure  is  essentially  granitic,  and  it  appears  to  belong  to  the  gabbro  (norite) 
variety  of  basalt. 

The  enstatite  is  clear  and  transparent.  It  shows  a  longitudinal  cleavage  parallel  to  the 
line  of  extinction,  and  in  some  specimens  this  is  crossed  by  a  cleavage  at  right  angles.  It 


*  Am.  Jour.  Sci.,  1846  (2),  ii.  380,  381. 
}  Ann.  Chem.  Pharm.,  1851,  hxix.  369-374. 
II  Ibid.  1864,  xxxviii.  225.  220. 
**  Ibid.  1870,  pp.  121-123. 


t  Ibid.  1848  (2),  vi.  411-414. 

§  Am.  Jour.  Sci.,  1855  (2),  xix.  163. 

If  Abb.  Berlin.  Akad.  1863,  pp.  117-122. 


200  BASALT. 

also  has  a  cleavage  which  is  often  well  marked,  and  divides  the  mineral  into  rhombic 
forms,  with  angles,  as  approximately  determined  by  several  measurements,  of  73°  and  107°. 
The  principal  cleavage  is  parallel  to  the  longer  diagonal  of  these  rhombs.  It  is  this 
rhombic  cleavage,  probably,  which  has  led  observers  to  believe  that  chladuite  crystallized 
in  the  monoclinic  and  triclinic  systems. 

The  enstatite  is  found  to  contain  mauy  glass  inclusions  with  polyhedral  outlines,  the 
planes  being  presumably,  as  usual  in  such  cases,  the  planes  of  the  inclosing  mineral.  While 
many  of  these  inclusions  are  arranged  in  the  eustatite  parallel  to  the  cleavage  planes, 
others  are  placed  at  every  angle  with  those  planes.  The  glass  inclusions  carry  bubbles, 
microlites,  and  rounded  lenticular  forms.  The  latter  are  frequently  at  the  end  of  the 
inclusion,  and  in  some  cases,  show  the  cherry-brown  color  of  some  chromite.  This  mate- 
rial, besides  forming  inclusions  in  the  glass,  is  in  lenticular  and  irregular  rounded  grains 
in  the  enstatite  itself.  It  sometimes  extends  in  a  series  of  grains  across  the  entire  eustatite 
mass,  and  at  others  is  in  isolated  forms.  These  inclusions,  microscopically,  are  seen  to  be 
composed  of  a  centre  of  nickeliferous  iron  or  pyrrhotite,  surrounded  by  a  band  of  dark 
material,  —  chromite  or  magnetite,  possibly.  These  ferruginous  materials  are  in  many 
cases  surrounded  by  a  yellowish-brown  staining  of  iron,  which  sometimes  extends  over 
considerable  of  the  mass  and  along  the  fissures.  Numerous  vacuum  or  vapor  cavities  were 
observed,  which  were  arranged  in  one  plane  of  the  enstatite.  The  inclusions  are  seen  to 
be  crossed  and  cut  by  the  cleavage  and  fissure  planes  of  the  enstatite,  showing  that  they 
were  of  prior  origin  to  the  fissures. 

The  feldspar  stands  next  in  abundance  to  the  enstatite,  and  is  in  irregular  masses  held 
in  its  interspaces.  It  is  water-clear,  and  almost  invisible  by  common  light.  Much  of  it 
is  seen  to  be  plagioclastic,  but  the  twinning  bands  are  so  exceedingly  fine,  and  the  polar- 
ization colors  so  bright,  it  does  not,  as  a  rule,  show  well  this  character,  except  with  high 
powers,  and  when  the  mineral  is  near  the  point  of  extinction. 

The  feldspars  contain  numerous  yellowish-brown,  dark,  and  almost  colorless  inclusions, 
which  are  sometimes  irregularly  scattered,  but  more  commonly  are  arranged  in  bands, 
similar  to  those  of  the  fluid  inclusions  in  quartz.  These  glass  inclusions  are  of  various 
dimensions,  and  many  contain  a  small  bubble.  Some  microlites  were  also  seen. 

In  the  feldspar  at  one  end  of  a  section,  the  enstatite  was  found  in  minute  crystals  ex- 
tending outward  from  a  centre,  forming  stellate  or  rosette-like  forms.  The  structure  is  like 
that  observed  in  terrestrial  rocks,  in  minerals  formed  from  alteration  or  solution.  This 
apparently  might  have  been  produced  in  this  case,  either  by  the  rapid  crystallization  of 
enstatite  material  in  a  liquid  feldspathic  mass,  or  by  secondary  alteration  through  water- 
action  on  the  rock  itself.  The  absence  of  any  other  signs  of  alteration,  except  of  the 
ferruginous  materials,  seems  to  negative  the  latter  supposition.  The  ferruginous  alteration 
can  probably  be  accounted  for  by  the  absorption  of  moisture  by  this  friable  fissured  stone 
since  it  reached  the  earth. 

The  bands  of  inclusions  were  seen  in  several  instances  to  extend  from  the  feldspar 
through  the  enstatite,  and  in  one  case,  to  pass  into  another  feldspar  on  the  opposite  side. 
This  indicates  that  the  cause  of  these  inclusions  was  a  general  one  for  the  rock-mass,  and 
not  limited  to  any  one  mineral.  Enstatite  was  found  in  a  few  cases  inclosed  in  the 
feldspar. 

The  monocliuic  pyroxene  or  augite  is  less  abundant,  and  its  determination  less  sure 
than  is  the  case  with  the  enstatite  and  feldspar.  It  is  crossed  by  fissures  in  a  very  irreg- 
ular manner,  but  shows  in  some  cases  the  approximately  right-angled  cleavage  of  augite. 
Its  optical  characters  appear  to  be  those  of  that  mineral,  but  its  polarization  is  more  bril- 


THE  METEOEIC  BASALTS.  —  GABBRO.  201 

liant  than  terrestrial  augite,  and  resembles  oliviue.  All  the  transparent  minerals  of  the 
section  are  clearer,  ami  lighter-colored  than  their  mundane  representatives,  and  hence  tend 
to  show  in  polarized  light  clearer  and  more  brilliant  colors;  The  augite  is  not,  however, 
quite  so  water-clear  as  the  eustatite,  but  has  a  very  i'aint  tinge  of  yellowish-green.  The 
1'iTMiginous  inclusions  are  the  same  in  this  as  in  the  enstatite. 

The  determination  of  the  olivine  is  more  doubtful,  since  it  is  seen  only  in  small  irreg- 
ular graius  and  masses,  which  hold  the  same  relation  to  the  other  minerals  that  the  olivine 
of  terrestrial  gabbros  usually  does  to  its  associated  minerals.  From  this,  and  the  fact  that 
it  optically  has  the  characters  of  oliviue,  it  is  here  assigned  to  that  species. 

From  the  description  of  the  mineral  constituents  of  this  meteorite,  it  would  seem  that, 
regarding  the  presence  of  the  feldspar,  Messrs.  Shepard  and  Waltershausen  were  correct, 
while  Eammelsberg  was  not.  It  shows  the  inability  of  the  ablest  rnineralogical  chemists 
to  draw  correct  conclusions  regarding  the  mineral  constituents  even  of  an  unaltered  rock. 
The  trouble  appears  to  reside  in  the  instrument  used  —  a  defect  in  the  method. 

Chladnite  ought  no  longer  to  be  regarded  as  eustatite  of  the  purest  kind,  as  stated 
in  most  mineralogies,  but  rather  as  a  mineral  aggregate  of  which  enstatite,  feldspar, 
and  augite  are  the  principal  constituents.  While  these  observations  gave  an  approximate 
solution  of  the  Bishopville  meteorite  puzzle  of  twenty-seven  years  standing,  it  would 
be  well  if  some  one  having  larger  amounts  of  this  meteorite  could  make  a  chemical 
analysis  of  it  as  a  whole,  and  also  analyze  the  minerals  by  the  modern  microscopic, 
specific-gravity,  chemical  method.* 

This  stone,  from  the  above  observations,  is,  in  its  mineralogical  composition,  structure, 
bubble-bearing  glass  inclusions,  and  microlites,  like  a  terrestrial  eruptive  rock,  and  it  is 
presumable  that  it  had  a  similar  origin. 

There  are  many  who  hold  that  the  terrestrial  eruptives  are  produced  by  the  aqueo- 
igneous  solution  of  chemical  precipitates  from  the  primeval  ocean  or  thermal  springs,  or 
from  sediments  buried  under  the  ruins  of  the  earth's  crust.  Would  it  not,  then,  be  in 
order  for  these  scientists  to  explain  the  formation  of  this  meteorite  in  the  same  way  ? 
Now  if  this  body  was  thrown  from  the  sun  or  a  similar  globe,  by  eruptive  agencies, 
would  it  not  then  be  proper  for  these  writers  to  speculate  how  this  sun  commenced 
with  a  cold,  inert  surface,  and  a  solid  interior ;  and  how,  later,  by  its  being  blanketed 
by  its  own  detritus,  it  had  been  raised  to  its  present  intensely  heated  condition  ?  — 
a  speculation  which  is  in  entire  accord  with  methods  formerly  advocated  by  ardent 
Wernerians  to  account  for  the  heated  condition  of  the  earth. 

Since  the  publication  of  the  preceding  description  of  this  meteorite,  Tschermak 
has  published  independently  another  description.  He  recognized  the  presence  of 
enstatite,  plagioclase,  and  pyrrhotite.f 

Manegaum,  India. 

The  Manegaum  meteorite  was  described  by  Maskelyne  in  1863,  as  composed  of  a 
probable  olivine  and  an  opaque  white  or  yellowish-white  mineral  The  latter  occurs 
as  a  flocculent  network,  iu  round  spherules,  in  fragments,  and  along  the  lamina?  of  the 
crystals  of  other  minerals.  Some  pyrrhotite  and  chromite  (?)  were  observed.  J 

In  1870,  Maskelyue  determined  the  supposed  oliviue  to  be  enstatite,  to  which  he 

*  Am.  Jour.  Sci.,  1883  (3),  xxvi.  32-36,  248. 

f  Die  mikros.  Besch.  der  Metcoriten,  1883,  i.  9,  10;  Sitz.  "Wien.  Akad.,  1883,  hxxviii.  (1),  363-365. 

{  Phil.  Mag.,  1863  (4),  xxvi.  135-139. 

26 


202  BASALT. 

also  referred  the  opaque  flocculent  white  mineral.  Minute  amounts  of  iron  were 
found.  The  analysis  and  composition  as  given  are  not  satisfactory,  and  it  is  thought 
that  a  more  extended  microscopic  examination  would  throw '  some  light  upon  tin: 
subject.  This,  like  the  Shergotty  meteorite,  is  probably  closely  like  the  gabbros  in 
structure.* 

Busti,  India. 

According  to  Tschermak,  this  is  composed  of  crystals  and  fragments  lying  in  a  fine- 
grained, splintery  groundmass,  all  composed  of  diopside,  eustatite,  plagioclase,  uickel- 
iferous  iron,  oldhamite,  and  osbornite. 

The  diopside  predominates,  and  has  a  gray  to  violet  color,  and  contains  rounded 
and  needle-shaped  crystals  arranged  parallel  to  the  fibrous  cleavage.  These  inclusions 
are  the  cause  of  the  violet  color. 

The  enstatite  is  in  colorless  splinters,  and  in  gray  cloudy  forms  replete  with  inclusions. 
These  often  show  a  polyhedral  contour,  and  are  filled  with  a  pale-brownish  glass,  bear- 
ing bubbles.  The  plagioclase  occurs  only  sparingly,  and  is  colorless  and  nearly  free 
from  inclusions.  The  oldhamite  only  appears  in  a  portion  of  the  rock  in  rounded 
grains  having  a  cubic  cleavage ;  the  osboruite  in  octahedrons  in  the  nickel-iron, 
which  occurs  only  sparingly.! 

ShalJca,  India. 

Tschermak  describes  this  meteorite  as  composed  of  a  clear-gray,  somewhat  friable 
mass,  with  inclusions  of  larger,  greenish-gray,  bronzite  grains,  and  blackish  chromites. 
Under  the  microscope  the  larger  bronzites  are  seen  to  lie  in  a  groundmass  of  bronzite 
fragments.  This  mineral  often  contains  brown  glass  inclusions  or  opaque  grains. 
The  last  are  arranged  in  the  fissures  in  the  bronzite,  and  are  referred  to  pyrrhotite. 
Some  greenish-yellow  grains,  regarded  by  Eose  as  belonging  to  olivine,  were  placed 
by  Tschermak  under  bronzite,  on  account  of  their  cleavage  and  action  in  acid.  J 

Ibbenbuhren,  Westphalia. 

The  meteorite  of  Ibbenbiihren  consists  of  a  grayish- white,  granular  mass,  in  which 
large  and  small  grains  of  a  light-yellowish-green  mineral  are  unequally  distributed. 
From  the  chemical  analysis  and  physical  character  of  this  mineral,  Von  Eath  referred 
it  to  bronzite,  and  to  the  same  mineral  he  assigned  the  groundmass,  regarding  the 
entire  meteorite  as  composed  of  bronzite  (diallage).  § ' 

According  to  Tschermak,  ||  the  bronzite  forms  the  principal  portion  of  the  stone, 
and  occurs  in  irregular  grains  of  varying  size.  Some  thin  lamime  were  referred  to 
augite,  and  some  little  colorless  grains  filling  the  interspaces  between  the  bronzite 
grains  were  looked  upon  as  plagioclase,  or  possibly  tridymite.  The  inclusions  are  in 
part  reddish-brown  glass,  and  in  part  opaque  grains  referred  to  chromite  and  iron. 

Greenland. 

On  account  of  its  interest  in  connection  with  the  occurrence  of  metallic  iron  in 
basalts,  a  description  of  the  iron-bearing  basalt  of  Greenland  is  placed  here  in  con- 
nection with  these  basaltic  meteorites. 

*  Phil.  Trans.,  1870,  pp.  211-213.  f  Die  mikros.  Bcsch.  der  Mctcoriten,  1883,  i.  9. 

J  Die  mikros.  Besch.  dcr  Mctcoriten,  1883,  i.  10.       §  Monats.  Berlin.  Akad.,  1872,  pp.  27-30. 
||  Die  mikros.  Besch.  dcr  Meteoritcn,  1883,  i.  10. 


THE  GREENLAND   BASALT.  203 

The  descriptions  are  in  part  taken  from  the  writings  of  others,  in  part  from  sections 
In 'longing  to  the  Whitney  Lithological  Collection,  and  in  part  from  sections  very  kindly 
sent  11113  by  Professor  J.  Lawrence  Smith  on  his  own  motion.  These  sections  were 
the  ones  which  had  been  used  in  the  preparation  of  his  "Memoire  sur  le  fer  natif  du 
Greenland,  et  sur  la  dolerite  qui  le  reuferme."  * 

One  section,  from  Assuk,  is  composed  of  a  gray  grouudmass,  sprinkled  with  little 
rounded  spots  of  a  darker  gray  color,  and  porpliyritically  holding  grains  of  feldspar, 
magnetite,  and  iron.  The  groundmass  is  composed  of  predominating  minute  augite 
crystals,  in  a  matrix  of  clear  glass,  containing  minute  feldspars  and  elongated  trichites, 
similar  to  those  seen  in  quartz  and  iron  ores.  The  structural  appearance  is  that  of  a 
mass  out  of  which  the  pyroxene  material  had  mainly  crystallized,  leaving  a  colorless 
gla-i.s,  which  in  part  had  yielded  feldspar  crystals  before  congelation.  The  feldspar 
crystals  are,  so  far  as  observed,  all  plagioclase.  A  greenish  secondary  product  not  only 
occurs  in  association  with  the  iron  ores,  but  also  in  detached  masses  and  bordering 
fissures.  Its  color  varies  from  a  bright  grass-green  to  a  dull  dirty-green.  Occasionally 
it  is  found  to  be  isotropic,  but  oftener  to  exhibit  aggregate  polarization,  and  it  may  be 
classed  under  that  convenient  name  for  these  variable  secondary  products — viridite. 
Little,  rounded  pale-pinkish  isotropic  grains  occur.  They  are  apparently  foreign,  and 
are  considered  to  be  garnet.  A  few  large  porphyritic  crystals  of  feldspar  were  seen, 
which  are  filled  in  the  interior  portion  with  inclusions —  microlites,  magnetite,  glass,  etc. 

The  darker  rounded  masses  observed  in  the  section  by  the  naked  eye  appear  to 
be  of  the  same  composition  as  the  rest  of  the  section,  but  with  smaller  crystals  on 
the  whole,  and  with  much  finely-disseminated  magnetite  dust. 

This  rock  has  been  described  by  Steenstrup  f  and  To'rnebohm,  J  the  former  giving 
a  plate.  Tornebohm  regards  the  augitic  mineral  as  enstatite,  stating  that  it  is  optically 
orthorhombic.  In  the  section  above  described,  the  mineral  is  clearly  monoclinic  in  its 
optical  characters,  although  it  is  perfectly  possible  that  a  rhombic  pyroxene  exists  in 
connection  with  the  augite.  The  iron  ores  occur  in  small  rounded  and  irregular 
grains,  partly  native  iron,  partly  magnetite  and  pyrrhotite.  Usually  a  border  of  mag- 
netite surrounds  the  metallic  iron. 

The  Ovit'ak  basalt  (dolerite)  is  described  by  Tornebohm  as  composed  of  plagioclase, 
augite,  olivine,  titauiferous  iron,  and  a  glassy  interstitial  material.  The  augite  is  in 
pale,  clear-brown,  almost  colorless,  irregular  particles  between  the  feldspars.  Olivine  is 
found  sparingly  in  little  grains,  which  as  a  rule  are  fresh  and  unchanged.  Bubble-bearing 
glass  inclusions  occur  in  the  augite,  olivine,  and  feldspar.  The  titaniferous  iron  is  in 
elongated  staff-like  masses.  The  interstitial  glassy  masses  appear  only  sparingly  in 
the  angles,  and  as  wedges  between  the  above  mentioned  minerals.  When  fresh  it 
is  of  a  fawn  color  and  usually  filled  with  microlites  or  dark  spheres.  Besides  these 
minerals  there  occur  metallic  iron,  pyrrhotite,  and  a  silicate  rich  in  iron.  This  last 
varies  from  a  green  to  a  dark-brown  color.  The  metallic  iron  appears,  in  part,  in 
silver-white  grains,  often  associated  with  magnetite,  and  sometimes  with  schreiber- 
site.  The  pyrrhotite  has  in  reflected  light  a  yellowish-gray  color,  and  is  in  larger 
and  smaller  grains  associated  with  the  other  iron  ores. 

The  silicate  rich  in  iron  falls  into  two  divisions :  one  a  beautiful  grass-green 
color,  isotropic,  and  allied  to  chlorophaeite ;  the  other  a  rusty-brown  mass,  sometimes 
isotropic,  and  sometimes  anisotropic,  and  here  referred  to  hisingerite.  § 

*  Aim.  Cliimie  Phys.,  1879  (3),  xvi.  452-505.  f  Min.  Mag.,  1877,  i,  143-148. 

{   Bibang  K.ni-1.  Svrnskii  \ctiMis.  Akad   llamll.,  1878,  v.,  No.  10,  pp.  18-21.  §   Ibid.  pp.  1-22. 


204  BASALT. 

Only  a  few  additions  will  be  made  to  Tornebohm's  description  from  Dr.  Smith's 
sections.  The  Ovifak  sections  have  the  usual  structure  of  a  diabase  or  dolerite ; 
divergent  crystals  of  plagioclase  lying  in  and  dissecting  the  irregular  masses  of  pale 
brown  augite,  iron  ores,  olivine,  etc.,  which  form  the  interstitial  material  between 
the  feldspars.  The  minerals  are  the  same  in  general  characters  as  those  described 
by  Tornebohm.  In  some  cases  the  glass  shows  the  globulitic  structure  common  in 
basaltic  glass. 

This  basalt  is  more  or  less  altered  in  the  different  sections,  presenting  many  of 
the  characters  of  a  diabase,  and  the  green  and  brown  silicates,  replacing  glass,  olivine, 
iron,  etc. 

Much  graphite  occurs  in  scaly  aggregations  of  a  black  color  with  a  lustrous  reflec- 
tion in  reflected  light,  and  associated  with  a  brown  and  violet-red  mineral  which  has 
been  referred  by  Tornebohm  to  spinel ;  but  in  the  section  examined  by  myself,  part 
has  been  found  not  to  be  isotropic,  and  has  been  considered  by  Dr.  Smith  to  be  corundum 
(1.  c.  pp.  484-486). 

The  reader  is  further  referred  to  the  before-mentioned  full  and  excellent  descrip- 
tion of  Tornebohm  for  a  more  extended  study  of  this  basaltic  rock;  as  well  as  to  the 
•writings  of  Tschermak.* 

One  section  in  the  Lithological  Collection  shows  a  grayish-white  groundmass  filled 
by  rounded  grayish-black  masses.  These  dark  spots  are  seen  under  the  microscope 
to  be  composed  of  plagioclastic  feldspars,  filled  with  an  irregular  network  of  granules 
and  masses  of  magnetic  and  native  iron,  the  whole  closely  resembling  the  structure 
of  some  portions  of  the  Estherville  meteorite  (Plate  III.  fig.  6).  The  interstitial 
portions  between  the  rounded  feldspathic-iron  masses  are  rilled  by  the  normal  basalt, 
composed  of  ledge-formed  plagioclase  crystals,  cutting  a  mass  of  yellowish-gray  augite 
grains,  violet-brown  globulitic  glass,  magnetite,  and  the  viriditic  products. 

In  some  parts  of  the  section  the  large  plagioclase  crystals  are  free  from  the  iron, 
and  contain  glass  inclusions  and  minute  pores.  A  little  olivine,  some  large  augites, 
and  yellowish-brown  hisingerite  (?)  was  seen  in  this  portion  of  the  section  which  has 
a  doleritic  or  diabasic  structure,  while  other  portions  have  that  belonging  distinctively 
to  the  fine-grained  basalts. 

Another  section  from  the  same  hand-specimen  shows  in  part  of  its  mass  the  same 
basaltic  structure  as  the  preceding,  of  plagioclase,  augite,  magnetite,  base,  and  secondary 
materials ;  but  the  remaining  portion  is  a  coarsely  crystallized  mass  of  olivine,  plagioclase, 
augite,  iron,  and  magnetite.  The  olivines  are  in  irregularly  rounded  grains,  traversed  by 
fissures.  They  are  sometimes  clear,  and  at  others  stained  yellowish,  and  are  altered  along 
the  fissures  to  a  yellowish  and  brownish  serpentine.  The  augites  are  pale-yellowish,  and 
with  the  olivines  contain  bubble-bearing  glass  inclusions,  iron,  magnetite,  etc.  The  usual 
secondary  products  occur  to  some  extent.  Some  of  Professor  Smith's  sections  have  parts  • 
similar  to  these  last  two  sections,  except  the  coarsely  crystalline  olivine-bearing  portion; 
but  his  are  more  altered,  and  contain  a  larger  amount  of  secondary  products. 

Two  of  Dr.  Smith's  sections  from  Pfaff-Oberg  are  seen  to  be  composed  of  lath-shaped, 
divergent  plagioclase  crystals,  lying  in  a  granular  groundmass  of  augite,  olivine,  etc.,  with 
various  secondary  products.  In  one  section  is  a  large  grain  of  iron,  of  an  irregular  cel- 
lular structure,  and  holding  in  its  cells  pyrrhotite,  olivine,  feldspar,  etc. 

The   preceding    descriptions   show   that    the   coarse   and  fine   crystalline    structure 

*  Miu.  Mitth.,  1874,  pp.  171-174. 


THE   METEORIC   BASALTS.  —  THEIR  STRUCTURE.  205 

is  not  dependent  on  age,  or  on  any  especial  depth  of  the  mass  at  the  time  of  the 
crystallization ;  also  that  diabase,  dolerite,  and  basalt  are  not  distinct  in  age,  but 
iiifivly  relative  terms,  indicating  coarseness  in  crystalline  texture  and  extent  of  alter- 
ation; for  sections  of  these  Greenland  basalts  could  be  pronounced,  by  taking  certain 
portions  of  them,  to  be  basalt,  dolerite,  diabase,  and  possibly  gabbro. 


Since  this  work  is  published  in  parts,  it  has  seemed  best  to  place  in  the 
first  portion,  so  far  as  possible,  all  relating  to  meteorites,  and  to  end  the 
first  part  before  taking  up  the  terrestrial  basalts. 

Owing  to  the  views  of  Professor  Tschermak,  that  nearly  all  the  mete- 
orites are  tufas,  the  preceding  descriptions  are  affected  by  that  view, 
since  most  of  the  microscopic  study  has  been  done  by  him.  It  appears 
to  the  writer  that  the  basaltic  meteorites  display  in  general  the  structure 
of  friable,  rapidly  crystallized  basalts,  apparently  quickly  cooled,  and  never 
bound  together  by  the  subsequent  products  of  alteration;  few  if  any  of 
them  being  fragments!.  From  this  point  of  view,  their  general  structure 
in  the  basaltic  variety  would  be  described  as  divergent,  lath-shaped  plagio- 
clase  feldspars,  lying  in  a  groundmass  of  pyroxene  (augite,  diallage,  and 
enstatite)  grains,  with  some  base,  feldspar,  and  iron  ores. 

So  far  as  the  gabbro  type  of  the  meteorites  is  concerned,  the  description 
of  the  Bishopville  form  would  serve  as  a  general  statement  of  their  collective 
characters,  varied  by  the  predominance  of  any  one  of  the  mineral  constitu- 
ents. The  Bishopville  form  is  certainly  not  fragmental  in  structure,  and  it 
does  not  seem  to  the  Avriter  that  the  other  meteoric  gabbros  are  so ;  hence  they 
may  be  defined  as  crystalline-granular  masses  of  feldspar,  pyroxene  (au- 
gite, diallage,  and  enstatite),  with  various  ores  of  iron,  and  with  or  without 
olivine.  In  these,  however,  certain  of  the  constituents  may  predominate, 
to  the  partial  or  complete  exclusion  of  others.  This  is  no  more  than  the 
observed  variation  occurring  in  different  portions  of  the  same  terrestrial 
rock. 

Although  mineralogically  the  basaltic  meteorites  could  be  divided  into 
many  varieties,  the  same  as  the  peridotites  have  been,  it  seems  to  the 
writer  unnecessary.  The  terrestrial  basalts  were  divided  in  the  first  place 
chiefly  on  structural  characters  and  differences  in  external  appearance, 
and  the  recently  introduced  terms,  norite,  olivine-giMro,  and  olmne-iiori/r, 
appear  to  be  superfluous  and  unnecessary,  although  consistent  with  the 
common  mineralogical  nomenclature  of  rocks,  since  structurally  all  can 
readily  be  classed  under  the  variety  gabbro. 


206  BASALT. 

Many  changes  in  the  arrangement  of  the  meteorites  may  hereafter  be 
made  by  the  writer,  if  ever  opportunity  should  be  afforded  for  an  ex- 
tended microscopic  study  of  them.  At  present  he  has  tried  to  arrange 
them  as  best  he  could  with  the  means  at  his  command. 

Although  all  the  chemical  analyses  found  of  the  basaltic  meteorites  have 
been  arranged  in  a  table,  they  are  too  few  and  too  imperfect  for  any  satisfac- 
tory discussion. 

SECTION  IT.  —  The  Pscudo- Meteorites. 

A  NUMBER  of  supposed  meteorites  have  been  described,  which  so  far 
as  their  general  characters  and  chemical  composition  show,  belong  to  the 
species  trachyte  and  rhyolite.  For  these  the  meteoric  origin  has  been 
denied  in  every  case,  and  perhaps  the  Igast  stone  is  the  only  one  which 
has  any  claims  to  be  considered  even  of  doubtful  meteoric  origin. 

Waterville,  Maine. 

This  pseudo-meteorite  has  teen  studied  by  the  present  writer.  It  is  in  the  form 
of  a  small  triangular  cinder-like  mass,  cellular,  laminated,  and  on  the  fresh  fracture, 
of  an  ash-gray  color.  The  laminated  appearance  is  produced  by  a  series  of  flattened 
cells  surrounded  by  a  black  vitreous  mass. 

The  original  surfaces  are  coated  with  a  gray,  red-brown,  and  bluish-black  crust  formed 
by  fusion. 

It  was  claimed  that  this  stone  was  picked  up  sbortly  after  falling,  hence  it  became 
necessary  to  examine  its  characters  to  see  how  long  it  might  have  been  exposed  to 
atmospheric  action.  The  portion  of  the  fused  crust  which  lay  uppermost  on  the 
ground  is  seen  under  a  lens  to  have  been  worn  and  polished  the  same  as  siliceous 
rocks  are  when  long  exposed  to  rain ;  while  the  remaining  parts  are  found  to  be 
coated  to  some  extent  by  earthy  material,  the  same  as  rocks  are  when  lying  in  a  dry, 
sandy  soil.  Its  cavities  contain  in  places  a  fine,  brown,  matted  mass,  formed  by  the 
fibres  of  growing  plants,  and  under  the  microscope  their  vegetable  character  can 
readily  be  distinguished. 

The  specimen,  then,  when  picked  up  by  Captain  Crosby,  could  not  have  been  a 
newly  detached  mass,  but  had  been  for  a  long  while  partially  buried  in  the  soil, 
and  of  course  could  not  have  been  a  portion  of  the  meteor  seen  shortly  before  the 
specimen  was  found.  It  remains,  then,  to  consider  the  very  improbable  supposition  — 
is  it  a  fragment  of  a  meteorite  which  fell  at  some  former  period  ?  Microscopically 
it  is  seen  to  be  a  cellular,  glassy  mass,  which  has  begun  to  devitrify,  and  presents 
the  appearance  of  a  slag-like  body  which  has  been  long  exposed  to  the  action  of 
atmospheric  agencies.  The  sections  were  cut  across  the  lamination,  and  showed  a 
ihiHal  structure  parallel  to  it.  A  few  quartz  grains  which  were  cracked  and  fis- 
sured were,  seen.  Near  the  fissures  numerous  ferruginous  globulites  had  been  de- 
veloped, and  the  quartz  showed  evident  signs  of  having  been  exposed  to  strong  heat. 


THE   PSEUDO-METEORITES.  207 

Adjacent  to  the  flattened,  as  well  as  some  other  cells,  is  a  black  and  brown  ferruginous 
material 

The  sections  show  not  the  slightest  characters  belonging  to  any  meteorite  that  has 
yet  been  examined  microscopically,  either  by  myself  or  by  others,  so  far  as  can  bo 
ascertained  by  their  published  descriptions.  It  is  apparently  a  slag.* 

Richland,  South   Carolina. 

This  so-called  meteoric  stone  is  reported  to  hav«  fallen  in  1846.  This  when  cut 
was,  according  to  Professor  C.  U.  Shepard,  of  a  "uniform  yellowish-white  color,  much 
resembling  that  of  common  fire-brick.  A  few  minute  grains  "of  transparent  quartz 
are  visible  throughout  its  substance,  which  is  otherwise  perfectly  homogeneous.  It 
is  close-grained  and  rather  firm  in  texture."  This  description,  and  the  chemical 
analysis  given  by  Shepard,  coupled  with  one  by  Rammelsberg  denotes  a  structure 
similar  to  that  of  the  rhyolites,  for  such  a  description  could  be  given  of  many  of 
them.f 

Jtammelsberg  regards  the  Richland  stone  as  a  clay,  or  possibly  a  fragment  of  a 
brick.  A  microscopic  examination  by  a  competent  lithologist  ought  to  readily  deter- 
mine the  character  and  origin  of  this  stone. 

Igast,  Livonia,  Russia. 

This  stone  is  looked  upon  by  Professors  Grewingk  and  Schmidt  as  an  authentic 
meteorite,  and  they  made  a  chemical  analysis  of  it,  showing  that  it  contained  a  little 
over  eighty  per  cent  of  silica. $ 

Professor  F.  J.  Wiik  also  accepts  it  as  a  meteorite,  and  states  that  in  the  thin  sections  it 
shows  a  fine-granular,  dark-colored  groundmass,  the  dark  color  owing  to  little  magnetite, 
porphyritically  inclosing  larger  crystals  of  quartz,  orthoclase,  and  oligoclase.  The  quartz 
contains  fluid  cavities  with  movable  bubbles,  and  the  plagioclase  shows  fine  parallel 
cleavage  lines  as  well  as  the  usual  twinning.  By  a  high  magnifying  power  is  shown 
in  the  groundmass  little  colorless  elongated  crystals,  and  minute  crystalline  grains. 

Professor  E.  Cohen  regards  it  as  a  doubtful  meteorite.  § 

Lasaulx  describes  this  as  a  stone  rich  in  a  basaltic  glass  base,  in  which  lie  inclosed 
numerous  grains  of  plagioclase,  microcline,  and  quartz.  The  groundmass  is  composed 
largely  of  a  brown  glass,  rich  in  magnetite  grains,  some  showing  quadratic  sections, 
and  others  a  dendritic  structure.  The  groundmass  further  contains  numerous  little 
spear-  or  ledge-shaped  plagioclase  crystals,  and  yellowish-green  irregular  grains  of 
augite  —  all  showing  fluidal  structure.  The  entire  groundmass  appears  as  the  product 
of  the  fusion  of  quartz  and  feldspar,  the  rudiments  of  which  are  now  inclosed,  witli 
the  later  crystallization  of  plagioclase  and  augite  out  of  the  molten  magma. 

Many  of  the  crystals  show  distinct  rounding  through  the  fusion  of  their  edges. 
The  larger  plagioclase  fragments  are  mostly  ragged,  slashed,  and  irregular,  while  the 
minute  quartz  grains  are  commonly  perfect,  and  smoothly  rounded.  The  plagioclase 
crystals  are  generally  clear  and  free  from  inclusions ;  only  an  external  rim  of  disjointed 
glass  inclusions  lies  about  them.  The  brown  glass  penetrates  into  the  fissure  in  the 

*  Am.  Jour.  Sci.,  1883  (3),  xxvi.  36-38.  f  Proc.  Am.  Assoc.  Adv.  Sci.,  1850,  iii.  147,  148. 

+  Arcliiv  Nat.  Liv-,  Elist-,  Kiirlands,  1S<H,  iii.  421-53 k 

§  Neucs  Juhr.  Mia.,  1883,  i.  384 ;  Finska  Vet.  Soc.  Forh.,  18S2,  xxiv.  63.  Arcliiv  Nat.  Liv-,  Elist-,  Kur- 
lands,  1SS2,  ix.  158. 


208  BASALT. 

crystals,  and  in  general  the  rock  appears  similar  in  character  to  one  produced  by  the 
partial  fusion  of  an  inclosure  of  sandstone,  granite,  or  some  other  rock,  in  basalt. 

After  further  description,  Lasaulx  decides  against  its  meteoric  character,  and  appar- 
ently justly.* 

Waterloo,  Seneca  Co.,  New  York. 

The  so-called  meteorite  of  Waterloo,  described  by  Shepard,f  is  considered  by 
Eammelsberg  to  be  a  clay.  \ 

Concord,  New  Hampshire. 

The  meteoric  stone  of  Concord,  described  by  Professor  B.  Silliman,  Jr.,  §  is  now 
preserved  in  the  collection  at  Yale  College. 

A  macroscopic  examination  by  the  writer  convinces  him  that  it  is  a  portion  of  the 
consolidated  scum  or  froth  of  some  slag,  and  this  opinion  seems  to  be  held  by  others.  || 

It  would  be  a  matter  of  the  greatest  interest  to  prove  the  fall  of 
meteorites  more  acidic  than  the  basaltic  variety,  and  it  is  not  impossible 
that  further  microscopic  studies  will  reveal  that  some  already  known  are 
of  the  andesitic  type. 

«  Sitz.  nieder.  Gesell.,  Bonn,  1882,  xxxix.  108-110.  f  Am-  Jour-  ScL>  1851  (2)>  xi-  39>  40- 

%  Jour.  Prakt.  Chetnie,  1863,  Ixxxv.  87,  88.  §  Am.  Jour.  ScL,  1847  (2),  iv.  353-356. 

||  G.  W.  Hawes,  Geol.  of  N.  H.,  part  iv.,  p.  24. 


EXPLANATION   OF  THE  TABLES. 


TABLE   I. — Chromite  and  Ficotite.     pp.  ii-v. 

THIS  table  contains  one  hundred  and  twenty  analyses  of  chromite  and  picotite,  arranged  in  the 
ruling  order  of  the  percentage  of  chromic  oxide.     Since  the  object  of  the  table  is  to  show  the  mutual 

relations  of  the  two  minerals,  and  their  variations,  many  of  the  analyses  given  of  chromite  are  of  the  more 

inquire  forms,  —  commercial  ores(()- 

TABLE   II.  — Siderolite.     pp.  vi-xv. 

This  table  contains  one  hundred  and  ninety-three  analyses  of  meteoric  and  terrestrial  irons,  arranged 
in  the  descending  order  of  their  percentage  of  iron.  The  irons  which  are  supposed  to  be  meteorites,  but 
which  have  not  been  known  to  fall,  have  Ixjen  marked  by  an  interrogation  point  placed  after  the  term 
Mi-te.ii-ite.  NII  variety  names  proper  occur  in  this  species;  but  for  convenience  the  meteoric  irons 
kimwii  to  have  fallen,  the  supposed  mete-uric  irons,  and  the  terrestrial  irons,  are  distinguished  from  one 
another  by  terras  placed  in  the  "Variety"  column. 

When  several  analyses  are  given  for  the  same  locality,  no  attempt  is  made  to  arrange  them  beyond 
this :  the  analysis  first  found  in  the  search  for  the  analyses  is  placed  first,  and  the  others  follow  in 
the  order  in  which  they  were  seen ;  except  in  cases  in  which  the  analyses  strikingly  differed  in  value, 
owing  cither  to  internal  evidence  or  to  the  reputation  for  accuracy  of  the  analyst ;  then  the  best  is 
placed  first,  but  the  order  of  the  others  still  remains  in  the  order  in  which  they  were  found. 

TABLE   III.  —  Pallasite.     pp.  xvi,  xvii. 

This  table  contains  twenty-four  analyses  of  meteoric  and  terrestrial  pallasites.  The  doubtful  meteor- 
ites are  designated  as  in  the  preceding  table,  while  the  terrestrial  forms  are  given  their  proper  variety 
name,  —  Cumberlandite.  But  few  of  these  analyses  are  accurate  exponents  of  the  constitution  of  the 
rock  mass,  the  majority  being  rough  approximations  only.  The  analyses  are  arranged  in  ascending  order 
of  the  percentages  of  silica. 

TABLE   IV.  — Peridotite.     pp.  xviii-xxxi. 

This  table  contains  two  hundred  and  forty-four  analyses  of  terrestrial  and  meteoric  peridotites.  In 
the  "  Variety "  column  is  given  the  name  of  the  variety  so  far  as  known,  and  when  the  specimen  is  a 
meteorite  it  has  been  designated  by  an  asterisk  prefixed  to  the  variety  name.  The  meteorites  whose 
variety  is  not  known  are  designated  by  the  term  Meteorite,  and  the  terrestrial  peridotites,  whose  variety 
is  also  unknown,  are  given  the  names  which  the  analysts  have  applied  to  them. 

The  analyses  have  been  arrangL-d  in  the  order  of  the  percentages  of  silica  ;  but  when  more  than  one 
exists  for  the  same  locality,  they  have  been  arranged  as  stated  for  Table  II. 

The  specific  gravities  in  this  and  the  other  tables  have  been  taken  from  any  available  source,  when 
the  analyst  has  given  none  ;  but  it  has  been  found  impracticable  to  designate  the  source  from  which 
they  were  obtained,  although  many  are  from  C.  Rumler's  determinations,  which  with  analyses  are  to  be 
found  in  the  works  and  tables  of  Partsch,  Buchner,  Rammelsberg,  and  Roth,  to  which  I  am  deeply 
indebted* 

Many  analyses  of  meteoric  forms  have  been  made  in  such  a  manner  that  no  determination  of  the 
complete  chemical  constitution  is  possible,  owing  to  the  omission  of  necessary  data  for  recalculation,  and 
all  such  have  been  omitted.  Many  others  have  been  recalculated  with  more  or  less  approximation  to  cor- 
rectneM,  varying  according  to  the  data;  matters  in  which  the  numerous  analyses  of  Dr.  J.  Lawrence 
Smith  have  been  particularly  unfortunate.  The  recalculations  have  mostly  been  made  by  the  aid  of 
a  four-place  table  of  logarithms,  and  therefore  pai-take  of  its  imperfections. 

TABLE  V.  —  Part  I.    The  Meteoric  Basalts,    pp.  xxxii,  xxxiii. 

This  part  contains  thirty -one  analyses,  arranged  in  order  of  their  percentages  of  silica. 

27 


TABLES. 


ii 


ANALYSES   OF   CHEOMITE  AXD   PICOTITE. 


TABLE  I.  — Analyses  of 


Name. 

Locality. 

Analyst. 

Publication. 

Cliromite. 
Picotite. 
Picotite. 
Picotite. 
Picotite. 
Picotite. 
Cliromite. 

Kynouria,  Greece. 
Knsakover,  Hohemia. 
Kosakover,  Bohemia. 
Hoihcim,  Bavaria. 
L.  Lhcrz,  France. 
L.  Lherz,  France. 
Near  Athens,  Greece. 

A.  Christomanos. 
F.  Farsky. 

Hilger. 
F.  Sandberger. 
A.  Damour. 
A.  Christomanos. 

Berichte  Cliem.  Gesell.  Berlin,  1877,  i.  343-350. 
Verh.  Geol.  Reich.,  1870,  pp.  '207,  208. 

Neues  Jahr.  Min.,  1866,  p.  399. 
Nencs  Jabr.  Min.,  1806,  p.  388. 
Bull.  Sue.  Ge'ol.  Frame,  1802  (2),  xix.  414. 
Berichte  Chem.  Gesell.  Berlin,  1877,  i.  343-350. 

Chrnmite. 
Chroroite. 
Cliromite. 

Pinuus,  Greece. 
Alt-Orsowa,  Hungary. 
Delos,  Grecian  Archipelago. 

Alfr.  Ilofmann. 
A.  Christonianos. 

Neues  Jahr.  Min.,  1873,  p.  873. 
BcTichte  Chem.  Gesell.  Berlin,  1877,  i.  343-350. 

Cliromite. 

Seres,  Macedonia. 

Cliromite. 
Cliromite. 
Cliromite. 
Cliromite. 
Chromite. 
Cliromite. 
Cliromite. 
Cliromite. 
Cliromite. 
Cliromite. 
Cliromite. 
Cliromite. 

Gythion,  Greece. 
Cerign,  Ionian  Isles. 
Hungary. 
Mt.  Il3'mettus,  Greece. 
Australia. 
Salamis,  Greece. 
Corinth,  Greece. 
Vrysi,  Greece. 
Vache  Island,  \V.  Indies. 
Var,  France. 
Loukissia,  opp.  Clmlcis,  Greece. 
Loutraki,  Greece. 

tl                      ft 

-  3.  Clouet.* 
A.  Christomanos. 
J.  Clouet, 
A.  Christonianos. 

tt            tt 
P.  Berliner. 
J.  Clouet. 
A.  Christomanos. 

Ann.  Cbimie  Phys.,  1869  (4),  xvi.  90-100. 
Berichte  Chem.  Gesell.  Berlin,  1877,  i.  343-350. 
Ann.  Chimie  1'livs.,  1809  (4),  xvi.  90-100. 
Bcrichte  Chem.  Gesell.  Berlin,  1877,  i.  343-350. 

«                          «                          tl                         H                         H                         It 

Ann.  Cbimie  Phys.,  1821,  xvii.  55-04. 
Ann.  Chimie  Phys.,  18B!»  (4),  xvi.  1)0-100. 
Berichte  Chem.  Gesell.  Berlin,  1877,  i.  343-350. 

Cliromite. 
Cliromite. 
Cliromite. 
Cliromite. 
Cliromite. 
Cliromite. 
Chromite. 
Cliromite  (Magnetic 
Chrome  Sand). 
Cliromite. 
Cliromite. 
Chromite. 
Chromite. 
Chromite. 
Cliromite. 
Chromite. 
Chromite. 
Chromite. 

Locris,  Greece. 
Perachora,  Greece. 
Peky,  Greece. 
Bare  Hills,  Baltimore,  Md. 
Alt-Orsowa,  Hungary. 
Christiania,  Norway. 
Shetland  Isles. 
Chester,  Penn. 

Prontheim,  Norway. 
Volterra,  Tuscany. 
California. 
Cerasia,  Euhcea. 
Haziskos,  Greece. 
Var,  France. 
Volo,  Thessaly. 
Troezene,  Greece. 
Epidaurus,  Greece. 

<t            tt 
ti            tt 

Henry  Seybert. 
Alfr.  Ilofmann. 

J.  Clouet. 
it 

T.  II.  Garrett. 

J.  Clouet. 
C.  Bechi. 
J.  Clouet. 
A.  Christomanos. 

L.  N.  Vauquclin. 
A.  Christomanos. 

it            tt            tt            it            tt            tt 

Am.  Jour.  Sci.,  1822  (1),  iv.  321-323. 
Neues  Jabr.  Min.,  1873,  p.  873. 
Ann.  Chimie  Phys.,  186'J  (4),  xvi.  90-100. 

Am.  Jour.  Sci.,  1852  (2),  xiv.  47. 

Ann.  Chimie  Phvs.,  1869  (4),  xvi.  90-100. 
Am.  Jour.  Sci..  1802  (2),  xiv.  02. 
Ann.  Chimie  Phvs.,  1809  (4),  xvi.  90-100. 
Berichte  Chem.  Gesell.  Berlin,  1877,  i.  343-350. 

Jour.  Mines,  1801,  x.  521-524. 
Berichte  Chem.  Gesell.  Berlin,  1877,  i.  343-3CO. 

11                         tt                         X                          tt                         It                          tt 

tt                tt                tt                tt                It                tt 

Chromite. 
Chromite. 
Chromite. 
Chromite. 
Cliromite. 
Chromite. 
Chromite. 
Chromite. 
Chromite. 
Cliromite. 
Chromite. 
Chromite. 

Nauplia,  Greece. 
Dry  ope,  Greece. 
Olympus,  Thessaly. 
Franklin,  Macon  Co.,  N.  C. 
Shetland  Isles. 
Volo,  Thessaly. 
Poros,  Greece. 
Baltimore,  Maryland. 
Baltimore,  Maryland, 
llaziskos,  Greece. 
Tinos,  Grecian  Archipelago. 
Ural. 

tt            it 

F.  A.  Genth. 
J.  Clouet. 
A.  Christomanos. 

Hermann  Abich. 
J.  Clouet. 
A.  Christonianos. 

tt                tt                tl                It                tl                It 
It                tl                tl                It                It                tl 

Geol.  of  North  Carolina,  1881,  ii.  31. 
Ann.  Chimie  1'hys.,  1869  (4),  xvi.  90-100. 
Berichte  Chem.  Gesell.  Berlin,  1877,  i.  343-350. 

Ann.  Physik  Cbemie,  1831,  xxiii.  335-342. 
Ann.  Chimie  Phys.,  1809  (4),  xvi  90-100. 
Berichte  Chem.  Gesell.  Berlin,  1877,  i.  343-350. 

Kokscharow's  Material  Min.  Russ.,  1806,  v.  163. 

Cliromite. 

Chromite. 
Cliromite. 
Chromite. 

Chromite. 
Chromite. 
Chromite. 
Cliromite. 
Chromite. 
Chromite. 

Australia. 

Wilmington,  Delaware. 
Bnlton,  Canada. 
Ltitzelberg,  Kaiserstuhl,  Ba- 
varia. 
Limne,  Eubcca. 
Andros,  Grecian  Archipelago. 
India. 
Mourtia,  Euboea. 
Alt-Orsowa,  Hungary. 
Ural. 

Schultz. 

J.  Clouet. 
T.  Sterry  Hunt, 
A.  Knop. 

A.  Christonianos. 
tt            tt 

J.  Clouet. 
A.  Christomanos. 
J.  Clouet. 

Rammelsberg's  llandbuch  der  .\Iineralcbemie,2d 
ed.,  1875,  p.  142. 
Ann.  Chimie  Phys.,  1869(4),  xvi.  90-100. 
Report  Prog.  Geol   Canada,  1847-48,  p.  164. 
Neues  Jabr.  Min.,  1877,  pp.  097-699. 

Bericbte  Chem.  Gesell.  Berlin,  1877,  i.  343-350. 

Ann.  Chimie  Phvs.,  1809  (4),  xvi.  90-100. 
Berichte  Chem.  Gesell.  Berlin,  1877,  i.  343-350. 
Ann.  Chimie  ljhys.,  1869  (4),  xvi.  90-100. 
Kokscharow's  Material  Min.  Russ.,  1860,  v.  164. 

Chromite. 
Chromite. 
Chromite. 
Chromite. 
Chromite. 

Ekaterinburg,  Russia. 
Lake  Meniphramagog. 
Hn/iskos,  Greece. 
Sagmata,  Greece. 
Ural. 

J.  Clouet. 
T.  Sterry  Hunt. 
A.  Christomanos. 

Ann.  Chimie  Phys.,  1809  (4),  xvi.  90-100. 
Report  Prog.  (ieol.  Canada,  1847-48,  p.  164. 
Berichte  Chem.  Gesell.  Berlin,  1877,  i.  343-350. 

Kokscharow's  Material  Min.  Russ.,  1866,  v.  163. 

Chromite. 
Chromite. 

Salonica,  Turkey. 
Samos,  Grecian  Archipelago. 

A.  Christonianos. 

Berichte  Chem.  Gesell.  Berlin,  1877,  i.  343-350. 

This  and  all  others  of  Clouet's  analyses  are  stated  to  be  the  mean  of  a  number  of  analyses. 


ANALYSES    OF    CHROMITE    AND    1'K'OTITK. 


Ill 


Chromite  and  Picotite. 


Sp.  Gr. 

A1A 

MgO. 

(  'r.A 

FeA 

FeO. 

SiO.2. 

CaO. 

Miscellaneous. 

Total. 

.TO  17 

17.27 

4.74 

230 

20.01 

13.20 

COj-1-H.jO—  4.45. 

98.20 

BO.JM 

17.87 

5.75 

2'-'  27 

8.77 

100.00 

•V'  IT 

1823 

701 

21   !•' 

1  25 

100.38 

r.:;  ;':; 

88.69 

7  ••:! 

11.40 

:;  ,sf> 

100.00 

,V.  :)l 

10.18 

7.80 

24.00 

1'.98 

100.00 

4  08 

68.00 

In.  /i 

8.00 

24  90 

200 

101.20 

80.80 

11.78 

'.I.Stl 

2.72 

7.00 

4.85 

5.50 

FeC().  =  87.76. 

100.20 

14.78 

6.13 

10.80 

2a.oe 

12  05 

6.17 

10.55 

CO.2—  2.27,  ll.,O  —  1.00. 

99.05 

lii.110 

21.101 

17006 

22.499 

14.211 

8.300 

99.317 

::  s.-, 

85.40 

17.7:! 

1081 

26.70 

7.20 

CO.,  =  2.80. 

100.49 

i  12 

-is  71 

17  --< 

560 

'.!  ,sa 

CO  ,  —  35.05. 

100.28 

tr:iri>. 

10.60 

21.16 

tract1. 

11  10 

12.04 

24.36 

CO.j—  18.14. 

100.46 

0.48 

10.92 

:;i  L'II 

27.72 

14.79 

11.30 

Mnr,Oi=4.18. 

100.59 

M  77 

1  1  S.-, 

31  48 

29.00 

7  ::o 

100.00 

20.60 

]  •'  I  IS 

3275 

23.84 

7.67 

2.01 

CO.j  —  1.03. 

99.88 

18.00 

17.IH 

33.20 

28.40 

8.00 

100.00 

19.61 

'.'  18 

3360 

"171 

403 

8.80 

COj  —  trace. 

10063 

.,.,  ?l 

18.68 

::i  7"> 

01)0 

IB  81 

943 

2.02 

100.35 

24.71 

7.81 

35.60 

28.62 

3.56 

1.55 

CO2  —  0.62. 

99.47 

81.80 

30.00 

37.20 

6.00 

loo.oo 

1::  !."» 

!•»  .">;! 

8700 

::i  7'i 

2  53 

10000 

17  no 

8.08 

3731 

380 

:;.".  l" 

2.82 

trace. 

Mn,Oj  —  1  12. 

1(025 

7.70 

16412 

::>  1" 

106 

2740 

8.53 

98.73 

27.  K] 

10.47 

39.06 

0.85 

1805 

2.10 

Mn.,0a  —  1.45. 

09.80 

688 

1407 

:;n  :;;', 

075 

27  70 

11  04 

!)'.!  42 

20.14 

1000 

89.60 

2820 

l.»l 

100.35 

10689 

l::.oo-_> 

::'.»514 

30.004 

10590 

!f.i.ll6 

20.6M 

17.005 

39.574 

10.558 

4.19 

98023 

4.80 

13.23 

4000 

37  77 

420 

KlOOO 

10.15 

10.80 

41.00 

23  14 

8.85 

100.00 

41.55 

02.02 

1.25 

104.82 

12.00 

21  28 

4200 

10  72 

500 

100.00 

I'.isl 

42  13 

83.98 

475 

100.66 

|::  M 

14.88 

42.20 

2384 

648 

100.00 

1097 

1  ">  ''7 

42  00 

19.02 

<)31 

2  20 

•i!)  97 

22.0  I 

12  72 

4280 

1933 

202 

1  13 

100.64 

•_'u.:;o 

4300 

3470 

200 

100.00 

81.19 

3.18 

43.20 

3062 

2  HI 

trace. 

100.33 

9.00 

12.86 

4323 

20  HO 

095 

4  70 

CO,  —  088 

99.03 

11.53 

21  oii 

4340 

2060 

4  87 

101.42 

20.15 

7.77 

43.50 

20.92 

6.02 

trace. 

99.20 

10.23 

16.26 

4.'!  70 

21  27 

542 

Mn,Og  —  1  95 

100.32 

2384 

0.77 

43  80 

81  55 

99.96 

4.31  a 

22.41 

15.67 

44.15 

5.78 

11.70 

99.77 

7.47 

17.:W 

41.20 

2493 

6  10 

loo.oo 

111  14 

300 

4479 

31  85 

200 

10084  • 

• 

0*08 

1  1  M) 

1  1  ^1 

21  41 

650 

574 

CQ2  —  I2i> 

1IKI-") 

18.86 

i'.'.Ki 

4491 

18  '17 

083 

98  25 

5.40 

4.09 

46.00 

4231 

3  20 

10000 

V.J  .,._> 

11  lit 

4510 

14  5') 

<;  to 

99.96 

10  1-2. 

028 

|.",  :;•' 

•':'.'  i  7 

!•'  42 

9871 

840 

23.77 

4540 

21  88 

."l  •>!', 

99  91 

4.534 

1M 

0.28 

4546 

I::  .;'.i 

10242 

0.00 

2.06 

16.60 

4278 

300 

10000 



820 

16.08 

46.90 

3508 

99.81 



20.00 

20.55 

464J7 

1"  D8 

10025 

8.71 

14.28 

47  30 

23  17 

6  20 

'i'i  70 



::.:;:; 

427 

47.50 

|.~,  •>•_> 

10032 



!i:;o 

6.00 

4750 

3"i  70 

1  50 

10000 

8.98 

2.88 

47.66 

trace. 

:;l  sr 

5.53 

W.71 

-  12.00 

15.01) 

4->  7-' 

|s  :;:', 

526 

10000 

... 

10.20 

4.68 

49.00 

•''.1  ''I) 

700 

10008 



(1.77 

18.40 

!'•  ri 

''3  27 

707 

1  nil.  IK) 



11.80 

18.13 

4  !i  7.-, 

21.28 

100  40 



21.67 

8  IK) 

50.06 

1  .".  70 

3  ia 

'.'li  1  1 

14''.') 

1    HI 

0  '17 

•'",  '10 

•)  --, 

4  80 

CO  —  0  75 

99  78 

5.00 

11.53 

60  sii 

''7  00 

4  90 

'i')  •':: 



11.87 

16.72 

r,o  so 

16.92 

1  '10 

'.i'i  •'! 



0.14 

17.05 

51.50 

22  75 

::  :,i; 

10000 

IV 


ANALYSES   OF   CHROMITE  AND   PICOTITE. 


TABLE  I. 


Name. 

Locality. 

Analyst. 

Publication. 

Cliromite. 
Cliromite. 
Cliromite. 

Vaclie  Island,  W.  Indies. 
Chester  Co.,  Penn. 
Ural. 

J.  Clouet. 
Henry  Seybert. 

Ann.  Cliimie  Phys.,  1809  (4),  xvi.  00-100. 
Am.  Jour.  Sci.,  1822  (1),  iv.  321-323. 

Cliromite. 
Cliromite. 
Cliromite. 
Cliromite. 
Cliromite. 

Philadelphia,  Penn. 
Tanagra,  Greece. 
Polyliieron,  Macedonia. 
Monterey  Co.,  Cal. 
Papades,  Eubcea. 

P.  Berliner. 
A.  Christomanos. 

E.  Goldsmith. 
A.  Christomanos. 

Ann.  Chimie  Phys.,  1821,  xvii.  55-04. 
Berichte  Chem.  Gesell.  Berlin,  1877,  i.  343-350. 

Proc.  Phila.  Acad.  Nat.  Sci.,  1873,  p.  305. 
Berichte  Chem.  Gesell.  Berlin,  1877,  i.  343-360. 

Cliromite. 

Styria. 

J.  Clouet. 

Ann.  Chimie  Phys.,  1869  (4),  xvi.  90-100. 

Karaliissar,  Asia  Minor. 

Cliromite. 
Cliromite. 

Wiasga,  Ural. 
Ural. 

A.  Laugier. 

Ann.  Mus.  Hist.  Nat.,  1815,  vi.  325-331. 
Kokscharow's  Material  Min   Russ    1800  v   163 

Cliromite. 
Cliromite. 

Hibbard's,near  Media,  Delaware 
Co.,  Penn. 
Ural. 

F.  A.  Genth. 

Sec.  Geol.  Survey  Penn.,  B,  1874,  p.  43. 
Kokscharow's  Material  Min   Russ    1866  v   103 

Cliromite. 

Albania. 

A.  Christomanos. 

Berichte  Chem.  Gesell.  Berlin,  1877,  i.  343-350. 

Chromite. 

Ann   Mines   1829  (2)   v  310  (ante  p   185) 

Cliromite. 
Cliromite. 
Cliromite. 
Cliromite. 

Cliromite. 
Cliromite. 
Cliromite. 
Cliromite. 
Pirotite    (Chrom- 
picotite). 
Cliromite. 
Cliromite. 
Cliromite. 

Vatondos,  Eubo3a. 
Broussa,  Asia  Minor. 
Plattsburg,  N.  Y. 
Texas,  Lancaster  Co.,  Penn. 

Smyrna,  Asia  Minor. 
Krieglacli,  Steiermark. 
Pyli,  Eubcea. 
Shetland  Islands. 
Dun  Mountain,  New  Zealand. 

Texas,  Lancaster  Co.,  Penn. 
Broussa,  Asia  Minor. 
Tarasska    Ural. 

A.  Christomanos. 

P.  Collier. 
Franke. 

A.  Christomanos. 
M.  H.  Klaproth. 
A.  Christomanos. 
T.  Thomson. 
Theodor  Petersen. 

C.  F.  Rammelsberg. 
A.  Christomanos. 

Berichte  Chem.  Gesell.  Berlin,  1877,  i.  .'!43-350. 

Am.  Jour.  Sci.,  1881  (3),  xxi.  123. 
Rammelslierg's  Ilandbuuh  der  Mineralchemie, 
2d  ed.,  1875,  p.  142. 
Berichte  Chem.  Gesell.  Berlin,  1877,  i.  343-350. 
Mineral  Korper,  1807,  iv.  132-136. 
Berichte  Chem.  Gesell.  Berlin,  1877,  i.  343-350. 
Ann.  Mines,  1827  (2),  i.  280. 
Jour.  Prakt.  Chemie,  1869,  cxv.  137-140. 

Handbuch  der  Mineralchemie,  2d  ed.,  1875,  p.  142. 
Berichte  Chem.  Gesell.  Berlin,  1877,  i.  343-350. 
Kokscharow's  Material  Min.  Russ  ,  1806  v  163. 

Cliromite. 

Mt.  Kossipnaia,  Ural. 

(1                          X                          U                         tt                          tt                     « 

Cliromite. 
Cliromite. 
Cliromite. 
Cliromite. 

Viatka,  Russia. 
Alt-Orsowa.  Hungary. 
O'ita,  Japan. 
Ural. 

J.  Clouet. 
Alfr.  Hofmann. 
T.  Haga. 

Ann.  Chimie  Phys.,  1869  (4),  xvi.  90-100. 
Neues  Jahr.  Min.,  1873,  p.  873. 
Jahresb.  Chemie,  1881,  p.  1302. 
Kokscharow's  Material  Min.  Russ.,  1866,  r.  163. 

Cliromite. 
Cliromite  (Crystal- 
lized). 
Cliromite. 
Cliromite  (Chrome 
Sand). 
Cliromite. 
Cliromite. 
Clmimite. 
Cliromite. 

Asia. 
Baltimore,  Maryland. 

Haziskos,  Greece. 
Chester,  Penn. 

Mourtia,  Eubcea. 
Baltimore,  Maryland. 
Texas,  Chester  Co.,  Penn. 
Ural. 

Alfr.  Hofmann. 
Hermann  Abich. 

A.  Christomanos. 
Isaac  Starr. 

A.  Christomanos. 
L.  E.  Rivot. 
T.  H.  Garrett. 

Neues  Jahr.  Min.,  1873,  p.  873. 
Ann.  Physik  Chemie,  1831,  xxiii.  335-342. 

Beriehte  Chem.  Gesell.  Berlin,  1877,  i.  343-350. 
Am.  Jour.  Sci.,  1852  (2),  xiv.  47. 

Berichte  Chem.  Gesell.  Berlin,  1877,  i.  343-350. 
Ann.  Chimie  Phys.,,1850  (3),  xxx.  200-203. 
Am.  Jour.  Sci.,  1852  (2),  xiv.  46. 
Kokscharow's  Material  Min.  Russ.,  1866,  v.  103. 

Cliromite. 

Ural. 

Kokscharow's  Material  Min.  Russ.,  18C6,  v.  102. 

Cliromite. 

Cliromite. 

Berezof,  Siberia. 
Massachusetts. 

A.  Moherg. 
C.  H.  Pfaff. 

Jour.  Prakt.  Chemie,  1848,  xliii.  114-128. 
Jour.  Chemie  Physik,  1825,  xiv.  101,  102. 

ANALYSES   OF   CHROJSUTE  AND   PICOTITE. 


Continued. 


Sp.  Gr. 

ALA- 

MgO. 

OA 

FeA 

FeO. 

SiOj. 

CaO. 

Miscellaneous. 

Total. 

51  03 

4840 

100.00 

')  7->o 

61.562 

36.14 

2.901 

MnO  =  trace. 

99.326 

6  20 

!•'  1'' 

51  60 

2406 

635 

100.33 

9  70 

51  00 

3720 

2.90 

99.00 

18.90 

7  81 

61  80 

"4  72 

2.05 

0.41 

100.69 

11  01 

17  45 

62  12 

1676 

2.00 

99.M 

!4  HUT 

2  18 

].|  .>!) 

62  12 

1524 

12  12 

09.00 

r  QO 

1''  (I'1 

5l>  50 

''4  7'' 

390 

O'.l  7  1 

3  0"' 

I'l   7'' 

5''  88 

1  22 

24  27 

12  05 

100.00 

800 

11  58 

5300 

•'1  '12 

250 

100.00 

762 

1''  31 

5300 

•>4  112 

2  15 

100.00 

805 

1098 

68.00 

"4  '.!•' 

305 

100.00 

1100 

.-,;;.<  H) 

34.00 

1.00 

MnO  =  trace,  Loss  =  1.00. 

100.00 

O.'.H) 

14  8*> 

.">:',  li; 

•'1  IK> 

1010 

100.08 

4  78 

698 

053 

6336 

741 

2ii.i;t 

NiO.,  =  0.14,  CoOo  =  trace, 

100.45 

1  30 

1526 

5360 

1083 

11.35 

MnO  =  0.39. 

101.34 

17  75 

203 

6390 

25.00 

0.80 

100.14 

11  14 

704 

5400 

18.08 

7.30 

CaCO2  =  2.44. 

100.00 

9  02 

5357 

6408 

25661 

4.833 

08.051 

785 

992 

5442 

24.88 

4.41 

101.48 

11  S2 

604 

54  55 

25.75 

1.95 

1(0.12 

5(1') 

0941 

64944 

31  507 

3.731 

3.405 

100.278 

675 

939 

65  14 

2888 

99.16 

482 

1058 

5550 

2625 

262 

060 

100.37 

4  00 

600 

55.50 

33.00 

2.00 

Ignition  =  2.00. 

1)8.50 

206 

721 

6584 

2480 

9.52 

00.43 

1300 

60.00 

3100 

trace. 

100.00 

4  115 

12  13 

1408 

66.54 

18.01 

MnO  —  0.46,  CoO+NiO  — 

101.22 

086 

989 

6655 

3023 

trace. 

97.63 

253 

1237 

5070 

2600 

2.04 

100.54 

580 

1238 

66.80 

2010 

4.20 

99.34 

(    480 

!•'  7-"> 

67.20 

20.00 

5.80 

100.61 

'     4.60 

633 

6692 

2700 

5.20 

100.05 

f     620 

12:58 

56.60 

2007 

5.00 

100.25 

1000 

1102 

68.00 

18.18 

2.20 

100.00 

1  1  UN; 

2.018 

68.0'JO 

21.337 

3.639 

MnO  —  0.002. 

99.688 

450 

080 

9  17 

5930 

28.27 

1  58 

!t9.  12 

000 

1029 

59.60 

22.41 

6.80 

100.06 

10001 

3.130 

60.022 

20.192 

0.026 

MnO  =  5.20. 

09.171 

1185 

7  45 

6004 

2013 

00  45 

840 

2.19 

60.50 

28.75 

045 

trace. 

100.29 

0.928 

60.836 

38.952 

0.019 

NiO  —  0.10. 

100.425 

1345 

631(?) 

61.50 

1895 

0775 

09.0?5 

1.96 

6337 

3004 

2.21 

202 

9'J.OO 

4.508 

63.39 

38.66 

NiO  —  2.28. 

104.33 

050 

12.12 

6380 

2034 

300 

0970 

(    5.04 

6400 

103 

ALol+Ftio 

2933 

99.40 

|    (5.15 

(i-J.  -Jo 

0.95 

30.05 

09.  40 

(    6.28 

63.40 

2.00 

28.00 

100.88 

10.83 

6.68 

6417 

1842 

0.91 

101.01 

77.00 

9.00 

AloOj+SiOj  —  15.00. 

101.00 

VI 


A  CLASSIFIED   LIST   OF   COMPLETE   (BAUSCH) 


TABLE   II. 


Variety. 

Locality. 

Analyst. 

Publication. 

Sp.  Gr. 

Fe. 

Ni. 

Co. 

P. 

S. 

P.Fe.Ni. 

Meteorite  ? 
Meteorite  1 

Meteorite  ? 
Meteorite  ? 
Meteorite  ? 

Meteorite  ? 

Meteorite  ? 

Meteorite  ? 

Meteorite  ? 
Meteorite  ? 
Meteorite  ? 

Meteorite  ? 
Meteorite  ? 

ri 

Meteorite  ? 

M 

(i 

Meteorite  ? 
<f 

Meteorite  ? 

« 

Walker  Co.,  Ala. 
Scriba,  N.  Y. 

Bonanza,  Coahui- 
la,  Mexico. 
Campbell  Co., 
Twin. 
Bedford  Co.,  Pa. 

Petropawlowsk, 
Siberia. 

Durango,  Mex. 

Prambanan,Java. 

Yanluiitlan,     On- 
xaca,  Mexico. 
Asliville,        Bun- 
combe Co.,N.C. 
Mexico. 

Hacienda  St.  Ro- 
sa, Mexico. 
Black   Mt.,    Bun- 
combe CO..N.C. 

Ruffs  Mt.,  New- 
berry,  S.  C. 
MurfVeesborout^li, 
Rutberford  Co., 
Tenn. 
Saropta,  Saratow, 
Russia. 
Coabuila,  Mex. 

Losttown,  Chero- 
kw  Co.,  Ga. 
Heidelberg,     Ba- 
den, Ger. 
San   Gregorio, 
Mexico. 
Chesterville, 
CliesterCo.,S.C. 
Iviinpuli,  Cal. 

Auburn,     Macon 
Co.,  Ga. 
Duel   Hill,   Madi- 
son Co.,  N.  C. 

Denton  Co.,  Tex. 

Cacliiuyal,     Ata- 
cama,  Chili. 
Wayne  Co.,  Ohio. 

San  Francisco  del 
Mezquital,   Du- 
rango,  Mexico. 

C.  U.  Shepard. 
C.  U.  Shepard. 

C.  U.  Shepard. 
J.  I,.  Smith. 
C.  U.  Shepard. 
(  Sokolowskij. 
f  Iwanow. 
(  M.  11.  Klaproth. 
(  J.  F.  John. 
t  M.vanderBoonMcsch. 
(  E.  11.  von  Baumhauer. 
L.  R.  de  la  Loza. 
C.  U.  Shepard. 
F.  A.  Genth. 

H.  Wichelhaus. 
C.  U.  Shepard. 
C.  U.  Shepard. 
G.  Troost. 

J.  Auerbach. 
J.  L.  Smith. 
C.  U.  Shepard. 
R.  Wawmkiewicz. 
J.  L.  Smith. 
C.  U.  Shepard. 
C.  U.  Shepard. 
C.  U.  Sheparcl. 
B.  S.  Burton. 
(  W.  P.  Kiddell. 
(  A.  Madelung. 
J.  Domeyko. 
J.  L.  Smith. 
A.  A.  Damour. 

Am.  Jour.  Sci.,  1847(2), 
iv.  74,  75. 
Am..  lour.  Sci.,  1841(1), 
xl.  300-309. 

Am.  Jour.  Sci.,  1867  (2), 
xliii.  384,  385. 
Am.  Jour.  Sci.,  1855(2), 
xix.  159. 
Am.  Jour.  Sci.,  1828  (1), 
xiv.  183-180. 
Archiv.    Kunde    lluss- 
land,  1841,  i.  317. 
Ibid.,  1841,  i.  72:3-725. 

Beitriige,  1807,  iv.  101, 
102. 
Jour.   Chemie   Phvsik, 
1821,  xxxii.  203,  264. 
Archives  Ne'erl.,  I860,  i. 
468. 
Ibid.,  pp.  405-468. 

Proc.  Pbila.  Acad.  Nat. 
Sci.,  1876,  p.  126. 
Am.  Jour.  Sci.,  1839  (1), 
xxxvi.  81-84. 
Am.  Jour.  Sci.,  1854(2), 
xviii.  239,  240. 

Ann.    Physik    Chemie, 
1803,  cxviii.  031-034. 
Am.  Jour.  Sci.,  1847(2), 
iv.  82,  83. 
Proc.  Am.  Assoc.  Adv. 
Sci.,  1850,  iii.  152-154. 
Am.  Jour.  Sci.,  1848  (2), 
T.  351,  352. 

Sitz.Wien.Akad.,  1804, 
xlix.  (2),  497. 
Am.  Jour.  Sci.,  1855  (2), 
xix.  100,  101. 
Am.  Jour.  Sci.,  1869(2), 
xlvii.  234. 

7.265 
7.50 

7.825 
7.05 
7.337 

"  7.70 

99.89 

99.08 

97.90 
97.54 
97.44 

97.29 

(  !I3II3 
}  94.12 

96.75 
91.50 

96.71 

I  93.77 
)  94.95 

90.58182 
96.50 

96.17 
96.92 
96.072 

90.04 
96.00 
90.00 

95.937 
95.82 
95.759 
95.472 
95.01 
95.00 
94.98 
94.58 
94.24 
94.02466 
92.099 
93.92 
93.01 
93.38 

0.25 

0.60 

0.12 

2.07 

7.00 
6.96 

3.25 

0.50 

2.86 

5.91 

4.83 

1.832 
2.60 

3.07 
8J 

3.203 

2.52 
3.121 
2.40 

2.657 
3.18 
3.66 
0.1 
4.22 
5.00 
4.52 
3.015 
5.17 
5.42982 
7.53 
4.93 
0.01 
5.89 

7.885 

2.00 

7.4816 
7.831 
7.824 

6.50-7.50, 
8.00 
831 

trace. 
0.42 

1 

7 
0.55 

trace, 
trace. 

.... 

trace 



1.046 

7.261 
7.01-7.10 

trace. 



1.315 

7.81 

0.35 
trace. 
0 
0.51 
trace. 

0.37 
trace, 
trace. 
0.39 
0.73 
0.39 

0.24 

1.256 
0.08 

0.24 

1802,cxxiii.252-_>.V>. 
Am.  Jour.  Sci.,  1871(3). 
ii.  335-338. 
Am.  Jour.  Sci.,  1849(2), 
vii.  449. 
Am.  Jour.  Sci.,  1880  (3), 
xix.  381,  382. 
Am.  Jour.  Sci.,  1809  (2), 
xlvii.  230-233. 
Am.  Jour.  Sci.,  1877  (3), 
xii.  439. 
Trans.  St.  Louis  Acad., 
1800,  i.  023. 
Buchncr,      Meteoriten, 
1863,  p.  193. 
Comptes  Kendus,  1875, 
Ixxxi.  597. 
Am.  Jour.  Soi.,  1864  (2), 
xxxviii.  385,  386. 
Comptes  Kendus,  1868, 
Ixvi.  573,  574. 

7.84 
7.818 
7.05 
7.0-7.17 
7.40 
7.0698 
7.42 

0.07 
0.129 
0.14 



0.001 
0.085 
0.13 
0.23 

7.901 

7.835 

ANALYSES  OF   METEORIC  AND  TEERE3TBIAL   KOCKS. 


vil 


Siderolite. 


c. 

Cu. 

Sn. 

Cr. 

Si. 

Al. 

Ca. 

Mg. 

Mn. 

Cl. 

As 

Insul. 

Loss. 

Umlet. 

M  iscellaneous. 

Total. 

trace, 
trace. 

trace. 
0.09 

trace. 

00.89 
09.97 

10000 
100.52 
99.00 

99.36 

100.03 
101.08 

100.00 
100.00 

10000 

100.00 
100.00 

100.00 
99.80 

09.60 
100.00 
100.931 

100.00 
99.121 
100.00 

99.940 
99.59 
99.999 
98.10 
99.82 
100.00 
99.67 
100.00 
10007 
99.78262 
09.03 
99.82 
100.48 
99.89 

0.20 

Accordingto  Meddle  itcon- 
tains   nickel,  potassium, 
nml    tracts    of  sodium, 
silicon,  sulphur,  cnrhon, 
phosphorus  !     and    tin  ? 
Phil.MaL'.,18(i2(4),xxiv. 
541. 
Ni,   CrjO,,   Co,    Mg,  and 
P  =  210. 

1.50 

trace. 

105 

1.60 

Graphite 

<•<•,". 
trace. 

Co  Si  and  loss  —  0.43. 

Co  and  Si  =  j  ^ 

0.00018 

Si0.2 
0.0056 

0.50 

Al,03 
0.61015 

CaO 

O.TOH15 

.... 

.... 

OA 

trace. 

.... 

.... 

0.20 

trace? 

0.57 

1  44 

trace. 

100 

0.017 

002 

:::: 

trace. 
0287 

trace? 

trace. 

.... 

.... 

trace. 

058 

0735 

.... 

trace. 

0.10 

The  carbon  occurs  as  gra- 
phite. 

. 

.... 

trace. 

2.2 
015 

ta 

0.32814 

SiO., 
0.20 

CaO 

MgO 

.... 

trace. 

0. 

30 

trace. 

—  

A   CLASSIFIED   LIST   OF   COMPLETE   (BAUSCH) 


TABLE   II. 


Variety. 

Locality. 

Analyst. 

Publication. 

Sp.  Gr. 

Fe. 

Si. 

Co. 

P. 

S. 

P.Fc.Ni. 

Meteorite  ? 

ti 
tt 

« 
tt 

tt 
tt 
tt 

tt 

tt 
tt 

n 

Meteorite. 
Meteorite  "> 

it 

Meteorite 
Meteorite 

jion  River,  Great 
Namaqualand, 
South  Africa. 
Scliwetz,    Weich- 
sel  Hiver,  Prus- 
sia. 
\elson  Co.,  Ken- 
tucky. 

\\Mintmannsdorf, 
Saxony. 

,iek    Creek,   Dn- 
vidson  Co.,N.  C. 
Coalmila,  Mexico. 

\ot  known, 
'ittsburg,  Penn. 

Tabarz,     Thurin- 
gia,  German  v  . 
GuilfordCo.,N"C. 

Vngarn,Jeniseisk, 

Siberia. 

Caille,  Var, 
1'rance. 

Southeastern  Mis- 
souri. 
lio  Juncal,  Ata- 
caina,  Cliili. 

3emdego    Creek, 
Baliia,  Brazil. 

Sizipilec,  Mexico. 

3raunau,      Bohe- 
mia. 

Dakota. 

Cosby  Creek, 
Cocke  Co., 

Tennessee. 

Cliulafennee,  Cle- 
burne  Co.,  Ala. 
Atauama,  Chili. 

Lenarto,   Hun- 
gary. 

Rowton,      Slirop 
shire,  Eng. 

Santa  Rosa,  New 
Granada. 

C.  U.  Shepard. 
C.  Rammelsberg. 

J.  L.  Smith. 
(  F.  E.  Geinitz. 
(  G.  E.  Lichtenberger. 

J.  L.  Smith  and  J.  B. 
Mackintosh. 
J.  L.  Smith. 

C.  U.  Shepard,  Jr. 
F.  A.  Genth. 
W.  Eberhard. 
C.  U.  Shepard. 
M.  A.  Gobel. 
f  L.  E.  Rivot. 
•{  J.  Boussingault. 
[  V.  de  Luynes. 
C.  U.  Shepard. 
A.  A.  Damour. 
JFickentscher. 
W.  II.  Wollaston. 
L  Wolilcr  &  Martius. 
C.  II.  L.  v.  Babo. 
Duflos  &  Fischer. 
C.  T.  Jackson. 

(C.  A.  Joy. 
•{  C.  Bergmann. 
!_  C.  U.  Shepard. 

J.  B.  Mackintosh. 
E.  Ludwig. 
f  J.  Boussingault. 
I  A.  Wherle. 

[  P.  A.  v.  Holger. 
W.  Flight. 

Rivero  and    Boussin 
gault. 

\rn.Jour.  Sci.,  1853(2), 
xv.  1-4. 

Vnn.   Physik    Cherpie, 
1851,  Ixxxiv.  153,104. 

Am.  Jour.  Sci.,  1800  (2), 
xxx.  240. 
^euc-s  Jahr.  Min.,  1876, 
pp.  008-612. 
Sitz.Isis,  Dresden,  1873, 
p.  4. 
Am.  Jour.  Sci.,  1880  (3), 
xx.  324-326. 
\rn.Jour.  Sci.  ,1869  (2), 
xlvii.  383-385. 
Vm.  Jour.  Sci.,  1881(3), 
xxii.  119. 
Am.  Jour.  Sci.,  1870(3), 
xii.  72,  73. 
Ann.     Cliem.     Pharm., 
1855,  xcvi.  280-289. 
\in.Juur.  Sci.,  1841  (1), 
xl.  309,  370. 
Bull   Acad    St    Peters 

7.45 
7.77 

93.30 
93.18 

93.10 
93.04 
94.59 
93.00 
92.95 
92.923 
92.809 
92.757 
92.75 
92.6346 

92.30 
92.70 
89.53 
89.73 
8763 

92.090 
92.03 
91.90 
95.10 

88.40 
91.89 
91.882 

91.735 

91.735 

91.035 
91.898 

9380 
94.033 

91.608 
91.53 
91.50 
90.90 

85.04 

91.25 
91.040 

91.23 

91.70 
91.41 

0.70 
5.77 

6.11 
6.16 
5.31 
5.74 
6.62 
6.071 
4.665 
5.693 
3.145 
7.1038 

6.20 
5.00 
9.76 
9.90 
7.37 

2.604 
7.00 
5.71 
3.90 
8.5 
6.32 
5.517 

0.532 
7.08 

5.816 
6.704 

4.00 
4.444 

7'368 
7.14 
8.58 
8.50 

8.12 

8.582 
*  , 
9.1 

8.21 
6.36 
8.59 

1.05 
0.41 

race. 

trace. 



0.05 
0.22 

6.21 

.... 



0.52 
0.48 
0.539 
0.395 
0.791 
trace, 
trace. 

trace, 
trace. 

0.36 
0.02 

trace. 

7.692 
7.589 
7.741 
7.737 
7.07 

0.562 

0.251 
0.862 

0.037 

0.277 

0.163 

1874,  xix.  544-554. 
Vnn.  Mines,  1854  (5),  vi. 
554,  555. 
Domptes  Rendtis,  1872, 
Ixxiv.  1287-1289. 
Ann.  Mines,  1844  (4),  v. 
161-164. 
Am.  Jour.  Sci.,  1869  (2), 
xlvii.  233,  234. 
Comptes  Rendus,  1808, 
Ixvi.  509-571. 
Buchner,      Meteoriten, 
1863,  p.  144. 
Phil.  Trans.,  1810,  pp. 
270-285. 
i'liipson,        Meteorites, 
1807,  p.  94. 
Buchner,      Meteoriten, 
1863,  p.  141. 
Ann.    Physik    Chemie, 
1847,  1-xxii.  475-480. 
Am.  Jour.  Sci.,  1863  (2), 
xxxvi.  259-261. 

Ann.     Chem.    Pharm., 
1853,  Ixxxvi.  39-43. 
Ann.   Phyrik    Chemie, 
1857,  c.  254,255. 
Am.  Jour.  Sci.,  1842  (1), 
xliii.  354-363. 

Am.  Jour.  Sci.,  1880  (3), 
xx.  74. 
Denks.    Wien.    Akad., 
1872,  xxxi.  187-1115. 
Comptes  Rendus,  1872, 
Ixxiv.  1288,  1299. 

7.428   | 
7.64 

-.015-7.112 
7.697 
7.731 
7.73 
7.468 

trace. 
0.62 

trace 
0.21 

.... 

5.00 

> 

.9 
1.58 
0.529 

trace 

trace 

0.809 
0.332 

0.37 

7.7142 
7.952   | 

0.01 
0.01 

0.190 
0.089 

7.257 
0.222   | 

0.50 
0.41 

0.17 
0.45 

7.7580 
7.73 
7.79 

0.605 

3.59 
0.371 

' 

77 

worterbuch,   1841,  p 
423. 
Zeit.  Phys.  Math.,  1830 
vii.  129. 
Phil.  Trans.,  1882,  pp 
891-890. 

Ann.     Chemie     Phys. 
1824,  xxv.  438-443. 

,.j 

( 

7  60      ^ 
7.30      j 

ANALYSKS    OF   METEORIC   AND   TEREESTKIAL   KOCKS. 


IX 


Continual. 


c. 

Cu. 

Sn. 

Cr. 

Si. 

Al. 

Ca. 

Mg. 

Mn. 

Cl. 

As. 

Insol. 

Loss. 

Undet 

Miscellaneous. 

Total. 

trace. 

K20  —  trace. 

100.00 

0.098 

100.098 

trace. 

99.67 

9942 

9990 

tract- 

0962 

trace. 

analyses. 

9907 

100.095 

0.031 

0.141 

98332 

100.38 

Fe^Oa-f-FeO  —  0  75 

9C645 

trace. 

0.0421 

trace. 

0.0505 

trace. 

Analysis  imperfect. 

100.00 

trace. 

0.90 

99.40 

0.12 

trace. 

0.90 

•  , 
O.E 

9^ 

99.20 
100.00 

0.12 

trace. 

0.2 

5 

100.00 
10000 

trace. 

trace. 

SiO.; 

trace. 

trace. 

Trace  of  Fe^Og. 

99.70 

9986 

046 

193 

10000 

10000 

0.07 

196 

10000 

9979 

Cu  -1  •  Mn  +  As  •+  Ca  +  Mp 

10000 

0.003 

0,0, 
trace. 

+Si+C+Cl+S=2.072. 

98.34 

O.OC3 

trace. 

SiO 

98.888 

0" 

10 

0.079 

0092 

Graphite  •  —  0  798 

99673 

0.175 

99  198 

0.10 

98.56 

0.10 

98.577 
99646 

trace. 

9953 

.... 

trace. 

030 

10038 

0.002 

100  10 

0.01 

0.77 

1.63 

023 

061 

10000 

trace. 

100  903 

trace. 

<t             << 

100  123 

W.7S 

•  

0.28 

98.12 
100.00 

A  CLASSIFIED   LIST   OF   COMPLETE   (BAUSCH) 


TABLE   II. 


Variety. 

Locality. 

Analyst. 

Publication. 

Sp.  Gr. 

Fe. 

Ni. 

Co. 

P. 

S. 

P,Fe,Xi. 

Meteorite  1 

Lagrange,       Old- 

J.  L.  Smith. 

Am.  Jonr.  Sci.,1861  (2), 

7.89 

91.21 

781 

0.25 

0.05 

Meteorite. 

liiiin  Co.,  Ky. 
Charlotte,     Dick- 

J.  L.  Smith. 

xxxi.  265,  200. 
Am.  Jour.  Sci.,  1875  (3), 

7.717 

91.15 

8.01 

0.72 

son  Co.,  Term. 
Jewell  Hill,  Mad- 

J. L.  Smith. 

x.  349-352. 
Am.  Jour.  Sci.,  I860  (2), 

91  12 

782 

0.43 

008 

« 

ison  Co.,  N.  C. 
Mexico. 

J.  L.  Smith. 

xxx.  240. 
Am.  Jour.  Sci.,  1868(2), 

7.72 

91.103 

7.557 

0.763 

0.02 

{B.  Silliman,  Jr.,  and 

xlv.  77. 
Am.  Jour.  Sci.,  1846  (2), 

I  7.40 

90.911 

8.462 

ied  River,  Texas. 

C.  U.  Shepard. 

Am.  Jour.  Sci.  ,1829  (1), 

(  7.82 
7.543 

90.02 

9.674 

t( 

Obernkirchen, 

F.  Wohler. 

xvi.  217-219. 
Gottingen,Nachrichten, 

7.12 

90.95 

V  r- 

80 

-    -    -J 

\ 

0.64 

Germany. 

f  J.  L.  Smith. 

18(53,  pp.  304-307. 
Am.  Jour.  Sci.,  1877  (3), 

7.78 

90.88 

8.02 

0.50 

0.03 

Smith's  Mt.,Rock- 
inghamCo.,N.C. 

1  F.  A.  Genth. 

xiii.  213,  214. 
Am.  Jour.  Sci.,  1877  (3) 

90  C8 

90 

7 

014 

f  A.  Madelung. 

xiii.  214. 
Buclmer,      Meteoriten, 

7.741 

90.764 

7.607 

0.889 

trace. 

- 

1'ierre,  Nebraska. 

1  H.  A.  Prout. 
f  Rivero   and    Boussin- 

1863,  p.  197. 
Trans.  St.  Louis  Acad., 
1800,  i.  711,  712. 
Ann.  Chimie  Physique, 

7.735 
7.00 

94.288 
90.70 

7.185 

7.87 

trace. 

Rasgata.New  Gra- 
nada. 

•1      gault. 
[F.  Wohler. 

C.  T.  Jackson. 

1824,  xxv.  442,  443. 
Ann.    Cliem.     Pharm., 
1852,  Ixxxii.  243-248. 
Am.  Jour.  Sci.,  1807  (2) 

7.33-7.77 
7692 

92.35 
9065 

6.71 

7867 

0.25 
001 

0.35 

trace. 

0.37 

i( 

Russell  Gulch.Gil- 

J.  L.  Smith. 

xliii.  280,  281. 
Am.  Jour.  Sci.,  1866(2), 

7.72 

90.61 

7.84 

0.78 

0.02 

pin  Co.,  Col. 
Franklin  Co.  .Ken- 

J. L.  Smith. 

xiii.  218,  219. 
Am.  Jour.  Sci.  1870  (2) 

7.692 

9058 

8.53 

0.36 

0.05 

tucky. 

A.  Lowe. 

xlix.  331-385. 
Neues  Jahr.  Min.,  1849, 

I 

90.471 

7.321 

trace. 

" 

Szlanicza,       near 

•  C.  Bergmann. 

p.  199. 

i 

91.301 

77  182 

7.323 
4  739 

0434 

trace. 
15.359 

Mts.,  Hungary. 

1857,  c.  256-260. 

( 

8942 

861 

A.  Patera. 

Neues  Jahr.  Min.,  1849, 

7.814   ] 

93.13 

5.94 

p.  199. 

94.12 

5.43 

::::.... 

f  Evan  Pugh. 

Ann.     Chem.     Pharm., 

•  •  J 

90.43 

7.62 

0.72 

0.15 

0.03 

0.56 

H 

Xiquipilco  Mex. 

•   W.  J.  Taylor. 

1850,  xcviii.  383-380. 
Am.  Jour.  Sci    1856(2) 

I 

87.89 
9072 

9.00 
8.49 

1.07 

0.44 

0.62 
0.18 

0.34 

LH.  B.  Nason. 

xxxii.  374-370. 
Jour.    Prakt.    Chemie, 

90.133 

1  *• 
7.2 

a 

0.376 

FeS. 
trace. 

f  E.  Uricoechea. 

1857,  Ixxi.  123. 
Jour.     Prakt.     Chemie 

00.40 

5.02 

0.04 

0.16 

2.C9 

" 

Toluca,  Mexico. 

|F.  Wohler 

1854,  Ixiii.  317,  318. 

86  073 

9016 

0.76!) 

1009 

1857,  Ixxxii.  243-247. 

90.23 

9.68 

tc 

Salt   River,  Ken- 

W. H.  Brewer. 

Proc.  Am.  Assoc.  Adv. 

!)0.51 

9.05 

:::::::: 

tucky. 

Sci    1851  iv  36  38 

9107 

9.08 

91.14 

905 

::  

(( 

Lenartu,    Hun- 

f W.  S.  Clark. 
•{  A.  Wehrle. 

Clark,  Metallic  Meteo- 
rites, 1852,  p.  40. 

7.73 
7.98 

90.153 
90.883 

6.553 
8.45 

0.502 
0.665 

.... 

0.482 

gary. 

[  P.  A.  v.  Holder. 

rites,  1852,  p.  40. 

7.72-7.80 

8504 

8.12 

3.59 

« 

Marshall  Co.,  Ken- 
tucky. 

J.  L.  Smith, 
r  A  Duflos 

1863,  p.  153. 
Am.   Jour.    Sci.,    1860, 
xxx.  240. 

7  63  771 

90.12 
1000 

8.72 
5308 

0.32 
0434 

0.10 

.... 

Seeliisgen,     Aus- 
tria. 

1848,  Ixxiv.  61-05. 

7.7345 

Fe+Mn 

92  327 

6228 

0607 

H 

W  T  Ricldell 

1848,  Ixxiv.  44:5-448. 

89993 

10007 

A   Wehrle 

1800,  i.  023. 

7  785 

89784 

8886 

0667 

Agram,  Croatia 

rites,  1852,  pp.  42-44 

ANALYSES   OF    METEOULC    AND   TEltttESTJUAL   ROCKS. 


Continued. 


c. 

Cu.      Sn. 

Cr. 

Si. 

Al. 

Ca. 

Mg. 

Mn. 

Cl. 

As. 

Insul. 

Loss. 

Undet. 

Miscellaneous. 

Total. 

.... 

trace. 
OOU 

99.32 
99.94 
99.46 
99.443 

99.873 
100.00 

90.00 
09.40 
100.00 
09.313 
102.473 
98.63 
100.11 
99.497 
99.20 
99.52 

99.196 
99.622 

99.997 

99.41 
99.07 
09.55 

90.88 
89.41 

10046 

100.00 
99.72 
98.234 

100.17 
99.82 
101.01 
100.46 

99.223 
99.998 
99.00 
99.26 
98.749 
100.00 
100.00 
.99.337 

trace. 

trace. 

0.50 

0.306 

003 

0.11 

.... 

trace. 

0.063 

0.35 

0.05 

trace. 

trace. 
002 

Silicates  =  0  08. 

0.95 

.... 

trace, 
tract-. 

Co,  C,  Si,  etc. 
1.404 
0.938 

Graphite  =  1.17. 
Co,  C,  Si,  etc.  =  1.41. 

O.'.HI 

.... 

Grapliile,  etc. 
0.34 
0.22 
Schreibersite,  graphite,etc. 
0.38 

O.o:; 
trace. 

020 

0.25 

0216 

2.034 

.... 

trace. 
trace. 

trace. 

1.11 
0.973 

Cr,08 

026 

M"O 

026 

Na/) 
trace, 
trace. 

026 

trace. 

026 

.... 

0.08 

0.082 

0  145 

1.226 

0.01 

0.77 

0.63 

023 

0.61 

Q.'j-2 

trace. 
0.104 
0.( 

v  -  ' 

I'J 

.... 

1.1.17 
0.026 

.... 

.... 

.... 

0.912 

.... 

0.834 
0  183 

.... 





e 

Xll 


A   CLASSIFIED   LIST   OF   COMPLETE   (BAUSCH) 


TABLE  II. 


Variety. 

Locality. 

Analyst. 

Publication. 

Sp.  Gr. 

Fe. 

Ni. 

Co. 

P. 

S. 

P,Fe,Ni. 

{M.  H.  Klaproth. 

Beitra^e  M  ineralkorper, 

7.73-7.80 

9650 

3.50 

Meteorite. 

Hraseliina,     near 
Agram,  Croatia. 

P.  A.  v.  Holger. 

1807,  iv.  99-101. 
limiimelsberg,       Hand- 

7.824 

83.29 

11.84 

1.26 

f  W.  S.  Clark. 

worterbuch,  1841,  422. 
Metallic         Meteorites, 

7.728 

89.752 

8.897 

0.625 

VIeteorite  ? 

Jurlington,  Otse- 

-  C.  H.  Rockwell. 

1802,  pp.  01,  62. 
Am.  Jour.  Sci.,  1844  (1), 

92.291 

8.146 

go  Co.,  N.  Y. 

C.  U.  Shepard. 

xlvi.  401-403. 
Am.  Jour.  Sci.  1847  (2) 

9520 

2125 

t( 

Ocatitlan,  Oaxaca, 

C.  Bergmann. 

iv.  77,  78. 
Jour.    Prakt.    Chemie, 

7+ 

89.71 

8.53 

0.56 

0.17 

H 

Mexico. 
Coopers  town, 

J.  L.  Smith. 

1857,  Ixxi.  57,  58. 
Am.  Jour.  Sci.,  1801  (2), 

7.85 

89.59 

9.12 

0.35 

0.04 

Robertson  Co., 
Tennessee. 
Putnam  Co.,  Ga. 

C.  U.  Shepard. 

xxxi.  266. 
Am.  Jour.  Sci.,  1854  (2), 

7.69 

89.52 

882 

(( 

San  Luis  Potosi, 

P.  Murphy. 

xvii.  331,  332. 
Proc.  Phil.   Acad.   Sci., 

7.38 

89.51 

8.05 

1.94 

0.45 

(( 

Mexico. 
Cartilage,  Tenn. 

E.  Boficky. 

1876,  pp.  123,  124. 
NeuesJahr.  Min.,  18C6, 

7.478-7.50 

89.465 

7721 

0.245 

0.093 

0.401 

<  G.  Bode. 

pp.  808-810. 
Ann.  Kep.  Smith.  Inst., 

7.3272 

89.22 

10.79 

trace. 

0.69 

Washington    Co., 
Wisconsin. 

}  J.  L.  Smith. 

1869,  pp.  417^19. 
Am.  Jour.  Sci.,  1869  (2), 

7.82 

91.03 

7.20 

0.53 

0.14 

u 

Butler,  Bates  Co., 

J.  L.  Smith. 

xlvii.  271,  272. 
Am.  Jour.  Sci.,  1877  (3), 

7.72 

89.12 

10.02 

0.26 

0.12 

II 

Missouri, 
'stlahuaca,  Mex. 

Cambria,  Niagara 

M.  Bucking. 
1C.  Rammelsberg. 
B.  Silliman  Jr.,  and 

xiii.  213. 
Ncues  Jahr.,  Min.,  1856, 
p.  304. 
Mon.Berlin.  Akad.,  1870, 
p.  444. 
Am.  Jour.  Sci.  1846(2) 

7.382 

89.073 
89.06 
92583 

7.29 
10.65 

5  708 

0.978 
0.08 

0.855 
0.17 

0.972 

Co.,  New  York. 

T.  S.  Hunt. 
D.  Olmsted,  Jr. 

ii.  374-376. 
Am.  Jour.  Sci.,  1845  (1), 

95.54 

5037 

xlviii.  388-392. 

7.5257  | 

94224 

6353 

{J.  Stolba. 

Sitz.Wien.  Akad.,  1804, 

6.005 

89.00 

8.84 

1.03 

Rokitan,      Bohe- 
mia. 

K.  R.  v.  Hauer. 

xlix.  (2-),  480-485 
Sitz.Wien.  Akad.  1864 

6394 

9600 

*( 

Victoria       West, 

J.  L.  Smith. 

xlix.  (2),  480-485. 
Am.  Jour.  Sci.,  1873  (3), 

7.692 

88.83 

10.14 

0.53 

0.28 

Cape      Colony, 
South  Africa. 

{J.  W.  Mallet. 

v.  107-110. 
Am.  Jour.  Sci.,  1871  (3) 

f  7.853 
1  7.855 

88.706 
88.305 

10.163 
10242 

0.396 
0.428 

0.341 
0.362 

0.019 
0.008 



ii.  10-15. 

I  7.839 

89.007 

9.964 

0.387 

0.375 

0.026 

Staunton,  Augus- 
ta Co.,  Virginia. 

J.  R.  Santos. 

Am.  Jour.  Sci.  1878(3) 

7688 

91.439 

7559 

0.608 

0.068 

0.018 

J.  J.  Berzelius. 
M.  H.  Klaproth. 

xv.  337,  338. 
Ann.    Physik    Chemie, 
1834,  xxxiii.  135-137. 

7.74-7.87 
7  80-7.83 

88.231 
97.50 

8.517 
250 

0.762 

trace. 

2.211 

« 

Elbogen,      Bohe- 

• J  F  John 

1815,  vi.  306-308. 

776 

8750 

875 

1.85 

mia. 

A  Wehle 

1821,  xxxii.  253-201. 

778 

8990 

8435 

0609 

P  A  v   Holger 

1863,  pp.  151,  152. 

9469 

247 

159 

a 

H  B  Geinitz 

1863,  pp.  151,  152. 
Neues  Jahr  Min    1808 

706 

88.125 

134 

trace. 

burg,  Germany. 

G  Troost 

pp.  459-463. 
Am  Jour  Sci    1845(1) 

87  58 

1242 

M 

Babb'sMill.Green 

•   C  U  Shepard 

xlix.  342-344. 
Am  Jour  Sci    1847  (2) 

7548 

85.30 

1470 

Co.,  Tenn. 

[  W  S   Clark 

iv.  70,  77. 

7839 

80594 

17  10 

2037 

H 

Tejupilco,  Mex. 
Howard  Co    Irul 

M.  Booking. 

1852,  pp.  65,  60. 
Neues  Jahr.  Min.,  1856 
p.  304. 
Am  Jour  Sci    1874  (3) 

7.326 

7  821 

87.092 
8702 

9.801 
1229 

0.766 
065 

020 

0.79 

0.73 

««    . 

vii.  391-395. 

7  20  7  58 

87  122 

10049 

0745 

123 

0.553 

Mexico. 

1857,  Ixxi.  57. 

7.62 

ANALYSES   OF   METEORIC   AND   TERRESTRIAL   ROCKS. 


Xlll 


Con/iiniof. 


c. 

Cu. 

Sn. 

Cr. 

Si. 

Al. 

Ca. 

Mg. 

Mn. 

Cl. 

As. 

Insol. 

Loss. 

Undet. 

Miscellaneous. 

Total. 

100.00 

0.68 

1.38 

0.48 

0«4 

K  =  0.43. 

100.00 

trace. 

0.703 

99.977 

100.437 

0.60 

Loss+S  —  2.176. 

100.00 

007 

MgO 

99.12 

99.10 

Sn  +  P  +  S  +  Mg  -t-  Ca 

100.00 

Cr.0, 

0.06 

=  1.66. 

100.00 

0002 

1.192 

99.719 

100.70 

0.45 

99.35 

001 

99.43 

0039 

99.207 

004 

100.00 

1  40 

99.991 

100.577 

100.577 

Graphite  —  0.87. 

99.74 

2.40 

SiO, 
1.10" 

CaO 

trace. 

99.50 

99.78 

0.172 

0.003 

0.002 

Si(  1  , 
0007 

0003 

99.872 

0.1  So 

0.004 

0.002 

0.001 

0.002 

99.659 

0  I''-' 

0003 

"I'M 

O.OoO 

0004 

99.947 

0.142 

0.021 

trace. 

0.108 

99.963 

0279 

10000 

100.00 

98.10 

0050 

100.00 

0.12 

019 

088 

99.94 

9.013 

1.321 

trace. 

SiO, 
trace. 

- 

99.799 

100.00 

trace 

trace. 

trace. 

100.00 

trace. 

0124 

99.859 

0.009 

0022 

99.204 

trace 

99.98 

C+Fe  —  0.624. 

99.117 

XIV 


A  CLASSIFIED   LIST   OF   COMPLETE   (BAUSCH) 


TABLE   II. 


Variety. 

Locality. 

Analyst. 

Publication. 

Sp.  Gr. 

Fe. 

HL 

Co. 

P. 

s. 

P.Fe.Ni. 

I  86  67 

8.12 

(>..-,<> 

I  P.  A.  v.  Ilolger. 

Zeit.PhysikMath.,1831, 

7.61-7.71 

1  83.67 

7.83 

n.<;u 

Meteorite  ? 

Boliumilitz,  Bohe- 

ix. 323-328. 

(  92.473 

5.007 

0  235 

mia. 

j  93.775 

3.812 

0.213 

ii 

Zacatocas,     Mex- 

[j. Mfi  in  nan. 
\  C.  Bergmarm. 
IS.  N.  Manross. 

Am.  Jour.  Sci.,  1831  (1), 
xix.  384-386. 
Neues  Jalir.  Min.,  1856, 
p.  207. 
Ann.   Cliemie    Pliarm., 

7.146 
7.48 
7.55 

94.06 
85.09 
92.33 

4.01 
9.89 

1  r 

7.3 

0.70 

.,    t 

8 

.... 

0.81 
0.84 

1.65 
042 

ico. 

H.  Muller. 

1852,  Ixxxi.  252-255. 
Quart.  Joiir.Chem.  Soc., 

f  7.20 
\  7.50 

89.84 
91.30 

5.96 
6.82 

0.62 
0.41 

6.25 

0.13 

1  859  (l),xi.  236-240. 

I  7.625 

90.91 

5.65 

0.42 

0.23 

0.07 

A.  E.  Nordenskibld. 

Geol.  Mag.,  1872(1),  ix. 

6.30,  6.86 

84.49 

2.48 

0.07 

0?0 

1.52 

T.  Nordstrom. 

518. 
Geol.  Mag.,  1872(1),  ix. 

7.05,  7.06 

86.34 

1.64 

0.35 

0.07 

0.22 

G.  Lindstrom. 

518. 
Geol.  Mag.  1872  (1),  ix. 

6.24 

93.24 

1.24 

0.56 

0.03 

1.21 

F.  Wohler. 

518. 
Neues  Jahr.  Min.,  1879, 

5.82 

80.64 

1.19 

0.47 

0.15 

2.82 

* 

It.  NauckliofE. 

p.  833. 
Miu.  Mitth.,  1874  p.  125. 

58.25 

2.16 

030 

0.16 

f  6.87 

91.71 

1.74 

0.53 

0.10 

91.17 

1.82 

051 

0.78 

82.02 

1.39 

0.76 

O.C8 

59.77 

1.60 

0.39 

i 

7.92 

93.89 

2.55 

0.54 

0.20 

Terrestrial 
Iron. 

Southern    Green- 
land. 

J.  Lorenzen. 

Zeit.neut.Gnol.  Resell., 
1883,  xxxv.  695-703. 

I   7.57 
J 

7.26 

92.41 
95.15 

0.45 
0.34 

0.18 
006 

.... 

trace. 



95.67 

trace. 

0.09 

702  729 

92.46 

0.92 

1.93 

0.07 

059 

92.68 

2.54 

058 

001 

706 

92.23 

2.73 

0.84 

94.11 

2.85 

107 

G.  Forchhammer. 

Ann.    Pbysik    Cliemie 

7.073 

93.39 

1.56 

0.25 

0.18 

0.67 

1854,  xciii.  155-159. 

1642 

93.16 

2.01 

080 

0.32 

0.41 

.                 ^ 

746 

90  17 

6  50 

079" 

.  Li.  bmith. 

080 

88.13 

2  13 

107 

0.25 

6.36 

760 

92.45 

288 

0.4:> 

0.24 

1.25 

{A.  A.  Hayes. 

Am.  Jour.  Sci    1845  (1) 

6.82 

83.572 

12.005 

Meteorite  ? 

Claiborne,  Clarke 
Co.,  Alabama. 

C.  T.  Jackson. 

xlviii.  145-156. 
Am.  Jour.  Sci.,  1838(1), 
xxiv.  332-337. 

5.75,  6.40, 
6.50 
6  035-7  944 

66.56 
81.20 

24.708 
1509 

256 

009 

2.00 



1854,  xv.  252. 

7  708 

82  77 

1432 

252 

026 

- 

Cape   of   Good 

Soelheim. 
A    Welirle. 

1867,  ii.  376-384. 
Zeit  Pliysik  Math    1835 

7605 

85.008 

12275 

0887 

Hope. 

M.  Bucking. 

(2),  iii.  222-229. 
Ann.   Cliemie    Pliarm., 
1855,  xcvi.  243-240. 
Zeit  Plivsik  Matli  1830 

7.604 

7318 

81.30 

7890 

15.23 
1528 

2.01 
100 

0.08 

trace. 

0.88 

C   T  Jackson 

viii.  283. 
Am  Jour  Sci    1872  (3) 

7  9053 

80  74 

1573 

ii 

iv.  495,  496. 

775 

04.00 

30  00 

M 

Brazil. 

Oktibbeha   Co 

W  J  Taylor 

Ixxxiii.  917-919. 
Am  Jour  Sci    1857  (9) 

6854 

3709 

5969 

040 

010 

Mississippi. 

xxiv.  293-295. 

ANALYSES   OF   METEORIC   AND  TEKliESTIUAL  HOCKS. 


XV 


Continual. 


c. 

Cu. 

Sn. 

Cr. 

Si. 

Al. 

Ca. 

Mg. 

Mn. 

Cl. 

As. 

Insol. 

LOBS 

Undet 

Miscellaneous. 

Total. 

.... 

.... 

.... 

.... 

.... 

0.82 
0.42 

0.41 

1.08 

o.ia 

0.10 

0.40 
0.68 

.... 

.... 

1.34 

4.78 

.... 



Be  =  0.10. 
Be  =0.12. 

08.16 
99.16 

100.00 
100.00 

100.00 
100.C2 

100.16 

99.63 

<J'J.97 
100.50 

100.00 
100.00 
99.79 
100.13 
102.04 
99.62 
99.43 
95.41 
89.60 
99.73 
100.46 
99.74 
100.25 
100.57 
98.80 
99.63 
98.87 

98.57 

99.18 
99.13 
99.03 
100.48  . 
100.00 

99.988 
99.89 
09.87 
98.77 
99.50 
100.00 
100.00 
100.00 
99.19 

1.025 

2.20 

Graphite,  etc.  =  1.12. 

C  -4-  Fc  =0.33.    Cliromite 
=  148. 

0.16 

0.03 

0.19 

trace. 

0.03 

3.08 
2.1'J 
2.17 
0.05 

.... 

trace. 

Si()., 
0.60 

.... 

.... 

trace. 

lo.h; 
3.71 
2.30 
3.09 
1.04 
1.37 
1.70 
1.27 
1.20 
0.28 
0.87 
0.96 
1.04 
3.11 
2.40 
BL3D 

1.69 
184 

0.27 
0.19 
0.19 

trace. 
0.24 

trace. 
0.48 

0.04 
0.29 
trace. 

072 

K2O  =  trace.        NIL/)  = 
"trace.     SiOo  =  trace. 
KaO=0.07.  KB./)  =0.14. 

K.,O=0.08,  Na  ,O=0.12,  In- 
e"ol.+SiO.  =0"6'J,I1=0  07. 
Silicates  -t-"Cr  +  Cu=0.08, 
O  =  11.19. 
FeO+Fe..Os=.°>0.43,  Nn.,O 
=0.09,  NiO+CoO=0.41. 

Sid.. 
0.00 

.... 

1.16 
0  10 

.... 

4.37 

.... 



0.13 
0.16 
0.10 
0.19 
0.23 
0.33 
0.48 
0.14 
0.06 
0.16 
0.20 
0.36 
0.23 
0.45 

0.12 
0.13 

SiOi 
0.20 
Sid, 
0.31' 
BIO, 

0.40 

Sid, 

OJ» 

Sid., 
0.39 
SiO., 
0.40 

Al.,08 
1.46 

AM., 
l.-'l 
Al,03 

Ma 

ALgj 

1.08 
Al.O. 
8.79 

CuO 
0.60 

MgO 
0.33 

.... 

0.10 

.... 

6.07 
2.39 
077 

.... 

U  =  0.28 

8.08 

•i'i  2:i 

1.48 

SiO.2 
0.90 
BiO. 

0.08" 
SiO., 

1  in" 

AI.O,, 
0.00 

AIA 

0.51 

467 

1.00 

109 

Sid, 
0.24 

1.09 

SiOj 
031 

008 

.... 

.... 

SiO, 
0.04 

Al,,0, 
O.U1 

1.99 

061 

SiO, 
0.38 

SiO., 
1.54" 

002 

2:!;: 
1.74 

0.48 
0.18 

Sid, 

trace, 
trace. 

008 

Silicates  =  4.20. 

1.31" 

.... 

trace. 

0907 

0401 

FeSi  =  2.395. 
Cr2O8+Mn  =  3.24. 

1  48 

•  *  •  • 

trace, 
trace. 

trace. 

0.95 

.... 

trace. 

trace. 

141 

015 

1  76 

1  34 

0.01 

P,  etc.  =  3.52. 

.... 

0.90 

.... 

.... 

0.12 

0.20 

0.09 

XVI 


A  CLASSIFIED   LIST   OF   COMPLETE   (BAUSCH) 


TABLE  III. 


Variety. 

Locality. 

Analyst. 

Publication. 

Sp.  Gr. 

SiO2. 

Fe. 

Fe20s. 

FeO. 

TiOj. 

Al.,03. 

Meteorite? 

H 
H 

(1 

}umber- 
landite. 

Meteorite? 

• 

H 
If 

Cumber- 

laiulitc. 

Cumber- 
landite. 

Meteorite  * 

tt 

H 

'ucsdii,  Arizona. 
Tucson,  Arizona. 

Bitburg,   Eifel, 
Prussia. 

Jraliin,  Minsk, 
Russia. 

Atacama,  Chili. 

j&nghult,  Swe- 
den. 

Singhur,  Decean, 
India. 

Anderson,  Hamil- 
ton Co.,  Ohio. 

Krasnoyarsk,    Si- 
beria. 

Atacama,  Chili. 

[ron    Mine    Hill, 
Cumberland,  It.  I. 

Taberg,  Sweden. 

Sierra  tie  Chaco, 
Atacama,  Chili. 

Rittersgrun,  Sax 
ony. 

Lodran,  India. 
Hainholz,  Prussia 

J.  L.  Smith. 

G.  J.  Brush. 

fJ.  F.John. 
[F.  Stromeyer. 

A.  Laugier. 

Von  Kobell  and 
Rivero. 

B.  Fernqvist. 
H.  Giraud. 
L.  P.  Kinnicutt. 
J.  J.  Berzelius. 

•  M.  H.  Klaproth. 
A.  Laugier. 
E.  Howard. 

C.  A.  Joy. 
T.  Drown. 

R.  H.  Thurston. 
C.  T.  Jackson. 
B.  Fernqvist. 

I.  Domeyko. 

C.  Winkler. 

G.  Tschermak. 
C.  Rammelsberg. 

Am.  Jour.  Sci.,  1855  (2),  xix. 
161,  162. 

Proc.  Cal.  Acad.  Sci.,  1803, 
iii.  30-35. 

Jour.  Chemie   Physik,  1826, 
xlvi.  386. 
Jour.  Chemie  Physik,  1826, 
xlvi.  386. 

Juchner,  Meteoriten,  1863,  p. 
139. 

\orrespondenz-Blatt     Verei 
nes    Kegensberg,   1851,   v. 
112. 

Clark,    Metallic    Meteorites, 
1852,  pp.  17-19. 

Akerman's    Iron   Man.,  Swe- 
den, 1876,  p.  xxxii. 

Edin.  Phil.  Jour.,  1849,  xlvii. 
56,  57. 

Ann.    Rep.    Peabody     Mus. 
Arch.,  1884,  iii.  381-384. 

Ann.  Physik  Chemie,  1834, 
xxxiii.  123-135. 

Diet.  d'Hist.  Nat.,  1818,  xxvi 
•259. 
Me'm.  Mus.  Hist.  Nat.,  1817, 
iii.  341-352. 
Diet,  d'  Hist.  Nat.,  1818,  xxvi 
259. 

Am.Jour.Sci.,1864(2),xxxvii 
243-248. 
Communicated   by  M.  Stan 
dish,  Esq.,  128  Broadway 
New  York  City. 
Bull.  Mus.  Comp.  Zoul.,  1881 
vii.  185. 
Geol.  Survey  R.  I.,  1880,  pp 
„  52-54. 
Akerman's  Iron   Man.,  Swe- 
den, 1876,  p.  xxxii. 

Ann.  Mines,  1864  (6),  v.  431- 
451. 

Nova  Acta  Leop.  Acad.,  Hal 
le,  1878,  xl.  333-282. 

Sitz.  Wien.  Akad.,  1870,  Ixi 
(2),  465-475. 

Mon.  Berlin.  Akad.,  1870,  pp 
322-325. 

6.52,6.91, 
7.13 

7.29 

6.52 
6.14 

6.20 
6.16 

6.46 

4.72-4.90 
4.72 
5.41 

3.02 
3.63 
5.50 

85.54 

81.56 

78.82 
81.80 

trace, 
trace. 

0.12 

(6.30 
|3.00 

13.CO 

20.39 

14.95 

Silicates 
l'J.50 

20.01 
20.43 

20.50 
16.00 
27.00 

20.G89 
20.85 

22.87 
23.00 

21.25 

23.34 

26.787 

29.41 
33.24 

87.35 
91.50 

60.27 
45.20 

69.16 
44.50 

44.021 

58.50 



4.09 
6.05 



0.01 

0.01 
8.95 

52 

v  ' 

85 

8.50 



7.03 
686 





68.20 

52.50 
48.298 

4.35 
3.56-4.05 

45 

44 
27.60 
43 

FeS 
14.10 

FeS 

7.226 

FeS 
7.40 

22.20 

10.417 

•,  • 
.62 

88 
12.40 

v  ' 

.45 
14.32 

3.53 

7.417 
3.51 

9.93 

9.99 
15.30 
6.30 

3.872 
5.55 

10.64 
13.10 
5.55 

4.10 

0.70 

0.188 
0.72 

3.82-3.88 

5.64 
4.29 

Fe+Ni 
3'J.OO 

Fe+Ni 
50.406 

Fe+Ni 
32.50 

4.12 

4.61 

ANALYSES  OF  METEORIC  AND  TERRESTRIAL  ROCKS. 


XVII 


Pallasite. 


.  

Cad. 

MHO. 

Mn<). 

P.A. 

S. 

Cr,03. 

Ni. 

Co. 

Cu. 

Sn. 

H./X 

Loss. 

Miscellaneous. 

Total. 

204 

p. 

0  12 

0.21 

855 

0.61 

0.03 

Analysis  of  .1  portion  freest  from  silicates. 

100.12 

Ca. 

i  it; 

2.4'! 

P. 

049 

Cr. 

9  17 

044 

008 

Cl  —  trace  

99.08 

1.10 

460 

810 

300 

Si  —  0.08  

100.00 

Mn. 

ii  "ii 

510 

11  90 

1.00 

100.00 

2.10 

1.85 

Cr. 
0.50 

260 

100.50 

2.00 
1568 

1.50 

trace. 

1.60 
5.73 

Insol. 
0.20 

Recalculated  on  the  supposition  that  the 

99.00 
98.58 

23  53 

430 

Insol. 
0.15 

silicates  compose  one  third  of  the  mass 
as  they  appear  to  do  in  the  specimen 
teen  by  the  present  writer. 
Recalculated  on  Clark's  supposition  that 

99.63 

1  80 

lO-'O 

030 

0  118 

0019 

1  40 

the  silicates  compose  one  half  Of  the 
mass. 

99.137 

4.24 

Analysis  very  imperfect 

92.93 

2280 

0.05 

P. 

•   »  «. 
633 

0.22 

trace. 

Recalculated  on  the  supposition  that  the 

99.94 

silicates  compose  one  half  of  the  mass. 

2307 

022 

5366 

0.228 

O.C 

33 

0.24 

Mg  —  0.025,     Mn  —  0.060,     C  —  0.021, 

101.27 

1925 

075 

100 

SnO  =  0.09.     Recalculated  on  the  sup- 
position that  the  silicates  comprise  one 
half  of  the  mass. 

100.00 

1500 

520 

050 

520 

300 

113.10 

1350 

675 

060 

99.25 

1.548 

4278 

0976 

P. 
0  115 

2693 

0477 

,V"IS 

0838 

004 

SnO2 
0.1  8'J 

Mn  —  3.75,  NiO+CoO  =  0.07. 

100.076 

073 

1645 

99.69 

O.C5 

567 

3 

1)5 

Zn  —  20.     Mean  of  several  analyses. 

100.00 

400 

2 

80 

100.00 

LOS 

1>  .;u 

040 

0127 

0013 

CnO 
002 

2 

GO 

99.06 

2.31 

3.66 

Na  <  ) 
0.22 

Recalculated,  but,  owing  to  some  doubts 

100.95 

0.60 

6.31 

N.-i.X  I 
0.4~8 

0.018 

regarding  the  original,  the  recalcula 
tiou  is  probably  faulty. 

Fe,Ni4P      P2P      Fe.,Si    Cr2Os-(-FeO 

97.032 

0.181 

2228 

0174 

0.149,      0.274,     0.169,         0.323. 
Recalculated. 

99.402 

30.52 

1  05 

286 

CrjOa+FeO  =  0.50. 

98.72 

XVI 11 


A   CLASSIFIED   LIST   OF   COMPLETE   (BAUSCH) 


TABLE   IV. 


Variety. 

Locality. 

Analyst. 

Publication. 

Sp.  Gr. 

Si02. 

M,0j. 

Fe. 

Fe,03. 

FeO. 

CaO. 

iF.  Pisani. 

Comptes  Rendus,  1864, 

26.08 

0.90 

830 

21.60 

1.85 

Meteorite. 

Orgueil,  France. 

lix.  132-135. 

S.  Cloez. 

Comptes  Rendus,  1864, 

2.50 

26.031 

1.2498 

.... 

14.236 

19.003 

2.322 

lix.  37-40. 

Meteorite. 

Murcia,  Spain. 

S.  Meunier. 

Comptes  Rendus,  1868, 

3.546 

29.224 

0.51 

13.63 

5.228 

0.09 

Ixvi.  G3U-642. 

Meteorite. 

Noblcbo  rough, 
Maine. 

J.  W.  Webster. 

Boston  Jour.  Phil.,  1824, 
i.  386-389. 

2.05  1  1 
3.092  ) 

29.50 

4.70 

14.90 

.... 



trace. 

Meteorite. 

Cold    Bokkeveld, 

f  E.  P.  Harris. 

Sitz.Wien.  Akad.,  1859, 

2.69 

30.80 

2.05 

2.50 

.... 

29.94 

1.70 

South  Africa. 

[  M.  Faraday. 

xxxv.  5-12. 
Phil.    Trans.,  1839,  pp. 

2.94 

28.90 

5.22 

33.22 

1.64 

83-87. 

f  J.  J.  Berzelius. 

Ann.    Physik    Chemie, 

1.94 

31.22 

2.36 

• 

.... 

29.03 

0.32 

1 

1834,  xxxiii.  113-123. 

Meteorite. 

Alnis,  Card, 

1  Commission  French 

Ann.  Physik,  1806,xxiv. 

1.7025 

30.00 

.... 

.... 

.... 

38.00 

France. 

Academy. 

195-208. 

I  L.  J.  Thenard. 

Buchner,      Meteoriten, 

•••••••• 

21.00 

.... 

.... 

.... 

40.00 

.... 

1863,  p.  20. 

Meteorite. 

Ornans,  France. 

F.  Pisani. 

Comptes  Rendus,  1868, 

3.599 

31.23 

4.32 

4.12 

.... 

24.71 

2.27 

Ixvii.  66:5-1  ill."). 

Meteorite. 

Little  Piney,  Mis- 

C. U.  Shepard. 

Am.Jour.  Sci.,  1840(1), 

3.50 

31.37 

0.49 

16.00 

.... 

17.25 

.... 

souri. 

xxxix.  254,  255. 

Meteorite. 

Dacca,  India. 

T.  Hein. 

Sitz.Wien.  Akad.,  1866, 

3.55 

32.05 

2.54 

10.38 

.... 

23.88 

1.12 

liv.  (2),  558-5(51. 

•Saxonite. 

Gnadenfrei,    Sile- 

Galle and  Lasaulx. 

Mon.  Berlin.  Akad.,1879, 

3.644  ) 

3.712  J 

32.11 

1.60 

25.16 

14.88 

2.01 

sia. 

pp.  750-771. 

3.785  ) 

Meteorite. 

Kernove,    Morbi- 

F.  Pisani. 

Comptes  Rendus,  1869, 

3.747 

32.95 

3.19 

22.25 



11.70 

1.89 

han,  Frnnce. 

Ixviii.  1489-1491. 

Picrite. 

Bystry  c,  Teschen. 

J.  Posch. 

Sitz.Wien.  Akad.,  1866, 

33.01 

15.83 

2.75 

7.62 

13.61 

liii.  (I),  272. 

Meteorite. 

Klein  -Wenden, 

C.  Rammelsberg. 

Ann.    Physik    Chemie, 

3.7006 

33.03 

3.75 

23.90 

.... 

6.90 

2.83 

Germany. 

1844,  Ixii.  440-404. 

Meteorite. 

lleredia,   Costa 

I.  Domeyko. 

Analcs  de   la  Universi- 

33.10 

1.25 

24.59 

16.97 

1.19 

Rica. 

daddeChile,  1859,xvi. 

3-25-339. 

Meteorite. 

Petrowsk,     Staw- 
ropol,  Russia. 

H.  Abich. 

Bull.  Acad.    St.  Pc'ters- 
bourg,    1860,  ii.  403- 

348  ) 
3.71  j 

33.16 

4.22 

4.32 



18.59 

1.20 

422,  433-439. 

Meteorite. 

Eichstadt,    Bava- 

{A. Schwager. 

Siiz.     Miinuhen    Akiid., 

3.70 

33.31 

2.31 

0.74 

ria. 

1878,  viii.  25-32. 

M.H.  Klaproth. 

Mem.  Acad.  Berlin,  1803, 

3.599 

37.00 

.... 

19.00 

16.50 

.... 

.... 

pp.  42-45. 

*Buchnerite. 

Grosmija,    Terek, 
Caucasus. 

Plohn. 

Min.   Mitth.,   1878,  pp. 
153-104. 

3.45-3.55  ) 

33.78 
34.02 

3.44 
3.46 

.... 

4.78 

28.86 
29.07 

3.22 
3.24 

Serpentine. 

Calagrande,   Tus- 

A. Cossa. 

Rie.  Chim.  Roc.  Italia, 

2.992-3.025 

33.863 

7.562 

.... 

12.073 

15.345 

4.614 

cany. 

1881,  p.  132. 

Meteorite. 

Saurette.     Vau- 

A.  Laugier. 

Ann.    Mug.  Hist.    Nat., 

3.4852 

34.00 

.... 

38.03 

.... 

.... 

.... 

cluse,  France. 

1842,  iv.  249-257. 

Meteorite. 

Kaha,  Hungary. 

F.  Wohler. 

Siiz.Wien.  Akad.,  1858, 

•  ....>.. 

34.24 

5.38 

2.88 

.... 

26.20 

0.66 

xxxiii.  205-209. 

Al,08 

-1-FeO 

Meteorite. 

Meno.Alt-Strelitz, 

J.  L.  Smith. 

Am.Jour.  Sci.,  1876  (3), 

3.65 

34.75 

16.54 

"17 

34 

1.44 

Mecklenburg. 

xii.  207-209. 

*Lherzolite. 

Zsadany,  Banat. 

W.  Pillitz. 

Zeit.    Analyt.    Chemie, 

34.88 

2.23 

1823 

11.09 

3.45 

1879,  xviii.  58-68. 

Serpentine. 

Chester,  Mass. 

E.  Hitclicock. 

Geol.  Mass.,  1841,  p.  160. 

3491 

10.27 

Meteorite. 

Epinal,    Vosges, 

L.  N.  Vauquclin. 

Ann.C4iimiePhys.,1822, 

3.666 

35.00 

22.00 

31.37 

France. 

xxi.  324-328. 

Meteorite. 

Khettree,    Rajpu- 
tana,  India. 

D.  Waldie. 

Jour.  Asiat.  Soc.  Bengal, 
1869,  xxxviii.  (2),  pp. 

3.743  ) 
3.612  $ 

35.17 

1.77 

18.79 



11.16 

2.37 

252-258. 

Meteorite. 

Vernon  Co.,  Wis- 

J. L.  Smith. 

Am.Jnur.  Sci.,  1876  (3), 

3.66 

35.24 

1.67 

15.72 

.... 

15.54 

1.41 

consin. 

xii.  207-20'.!. 

Meteorite. 

Borkut,  Hungary. 

J.  Nuricsany. 

Sitz.  Wion.  Akad.,  185G, 

5.242 

35.28 

2.74 

27.03 

4.71 

1.95 

xx.  398-406. 

*Dunite. 

Chassigny,  Haute 

A.  A.  Damour. 

Comptes  Rendus,  1862, 

3.57 

35.30 

.... 

.... 

26.70 

.... 

Marne,  France. 

Iv.  591. 

*  The  prefixed  asterisk  indicates  that  the  specimen  is  a  meteorite. 


ANALYSES   OF   METEORIC   AND   TERRESTRIAL   ROCKS. 


XIX 


Peridotite. 


KgO. 

MnO.    -NaX). 

K.U. 

Cr40a. 

Ni. 

Co. 

Cu. 

Sn. 

P. 

S. 

HjO. 

Miscellaneous. 

Total. 

17.00 
8.0711 

24.80 

&ao 

19.20 
B.31 

11.00 
9.00 
24.40 

25.88 
22.90 

17.03 

23.68 
7.28 
23.04 
20.39 

29.24 

18.86 
21.50 
18.66 

23.72 

18.092 
14.50 
B.89 

lO.lfi 
41.!ll 
4.25 

23.80 
82.05 

::i.7i; 

0.30 
1.9302 

2.20 
1.323 
0.35 

0.19 
0.32G5 
trace. 

Cr2O3+FeO 
"  0.41) 

ftJX 

oases 

CrjOj-rFeO 

"   0.-J2 

4.00 
0.70 

0.70 
C.,Oa+FeO 
0.63 
Cr208 
2.00 

1.00 
FeO+Cr.,O3 
0.40" 

NiO+CoO 
2.20 

NiO 

2.0057 

1.36 
2.30 

mo 

1.30 

0.82 
NiO 
1.88 

Ni 
2.00 
NiO 
3.60 

NiO 

•2.88 
Ni,  <"r,  Co  * 
428 

1.63 

3.92 
1.55 

5.75 

H.,SO4  =  1.64,  II  ,SO,  =  0.53, 
Cl  •=  0.08,       H/)  -|-  organic 
matter  =  10.81. 
II_,S(  )4  =  2.3345,    C!  =  0.0770. 
"Organic  mutter  =  0.41.    Am- 
m»nia=0.1042.    H.1O=7.812. 
FeS  =  20.52. 

100.00 
09.472 

99.758 

98.50 
98.79 
100.44 

CoO 
0.0904 

4.0460 

7.812 

18.30 

0.97 

026 
Mn. 
B.OO 

2.00 
trace. 

trace. 
0.07 

trace, 
trace. 

0.03 

.... 

trace. 

3.38 
4.24 

6.50 

C  =  1.07.    Bituminous  matter 
=  0.25.     • 

1. 

trace. 

a 

Insol.  =  8.09. 
C  =  2.50.     IL,O+loss  =  9.60. 
C  =  2.50.    HoO+loss  =  18.60. 
Fe,  Xi  =  1.85. 
S-t-P?+loss  =  4.73. 
NiO  =  0.80. 

0 

80 

' 

100.00 
100.00 
99.42 
100.00 
98.47 

90.85 

100.77 
08.70 
100.01 
00.87 

90.24 

99.15 
10000 
100.00 
100.07 
99.913 
100.00 
98.50 
98.99 
109.79 
100.00 
90.87 

101.31 

100.51 
98.40 
9M» 

350 

0. 
trace. 
1.50 

0.70 

">'> 

.... 

trace. 

trace. 

2.69 

.... 

0.07 

trace. 

0.11 

.... 

0.05 

PA 

truce. 

0.78 

1.87 
2  15 

.... 

0.57 

O203+FeO 
trace. 

1. 
0.59 
0.28 
0.88 

1.40 
1.04 

tl 
1.81 
0.38 
0.04 

0.60 
0.40 

4.23 

CO.2  =  11.07,       LljO  =  trace. 
Rock  altered. 

0.62 

2.37 
1.51 

NiO 

3.81 

0.94 
1.50 

.... 

0.05 

0.08 

0.02 

2.09 

Recalculated. 

C  =  trace. 

Fe+P  =  24.04. 
Loss,  etc.  =  4.60. 

FcS  =  5.37,     C0.2  =  0.08. 
Fresh  portion. 
CO.,  =  0.08.    Kxterior  portion. 

TiO.2  =  0.080.  Ignition  ;=  5.808. 
HoO+loss  =  3.31. 
FeS  =  3.55,   C  =  0.68. 
FeS  =  4  24.     Recalculated. 

C  =  0.21,  Mn  =  1.64,  Cr2O3+ 
FeO  =  0.56. 
Loss  =  0.40. 

CaO+K./>  =  1.25. 
Cr  =  0.10.    Loss  =  2.00. 

FeS  =  4.60.     Recalculated. 
Xi  +  Mn  =  0.78.    Recalculated. 
Chromite+Pyroxene  =  3.77. 

0.15 

.... 

.... 

SnO. 

1.10" 

.... 

1.60 
1.42 

.... 

trace. 
MM. 
0.83 

0.05 
trace. 

0.63 
0.03 

030 
0.30 

0.17 
0.17 

1-f 

0.33 

1.37 
1.36 

2.77 

">00 

0.94 
0.31 

0.30 

Cr,O,+FeO 
0.89 

trace. 
0.02 
trace. 

0.01 
trace. 
0 

03 

trace, 
trace. 
0.45 

2.64 

9.45 

4.31 

0.94 

0.25 
0.40 

NiO 
0.60 

1.20 

128 
14 

225 

.... 

0.87 

1.01 

trace. 

0.21 

0.07 
4 

trace. 
0 

08~ 

0.12 

trace. 
0.03 

1.70 
0.89 



0.45 

IM 

0.60 
0.60 

Cr.o.  +  FeO 
"  0.04 

0.76 

t  1'robnlilj  a  Misprint  for  3.05.    liuclmer,  Meteoriten,  1863,  p.  40. 


XX 


A   CLASSIFIED   LIST   OF   COMPLETE   (BAUSCH) 


TABLE  IV. 


Variety. 

Locality. 

Analyst. 

Publication. 

Sp.  Gr. 

SiO.2. 

A1203. 

F, 

Fe203. 

FeO. 

CaO. 

*Dunite. 

Chassigny,  Haute 

L.  N.  Vauquelin. 

Ann.CliimiePhys.,]816, 

33.00 

31.00 

Marne,  France. 

i.  4!)-54. 

Meteorite. 

Warrenton,    Mis- 

J. L.  Smith. 

Am.  Jour.  Sci.,  1877  (3), 

3.47 

35.63 

0.13 

1.78 

30.44 

1.41 

souri. 

xiv.  222-224. 

F.  Crook. 

Chem.      Const.      Met. 

3.50 

35.047 

2.307 

8.00 

.... 

34193 

1.776 

Stones,  ]>p.  21-26. 

Meteorite. 

Ensisheim.Elsass, 

C.  Barthold. 

Jour.    Phvsique     1800 

3.233 

4200 

17.00 

20.00 

2.00 

Germany. 

1.  l<;!M'7<i. 

Foucroy   and  Vau- 

Ann.  Mus.    Hist.  Nat., 

3.4884 

50.00 

30.00 

1.40 

quelin. 

1804,  iii.  108-112. 

Serpentine. 

Radauberg,  Harz. 

A.  Streng. 

Neues  Jalir.  Min.,  1802, 

2.71 

35.67 

298 

.... 

6.04 

4.95 

0.18 

..  pp.  541,  542. 

Meteorite. 

Stillldale.Dalecar- 

G.  Lindstrom. 

Ofversigt  Kongl.  Veten. 

3.733-3.745 

35.71 

2.11 

21.10 

•  *  <  * 

10.29 

1.01 

lia,  Sweden. 

Korhan.,  1877,  p.  35. 

Meteorite. 

Albarello,    Mode- 

P.  Maissen. 

Gazzetta  Cliemica,  1880, 

35.913 

4.479 

4.332 

24.313 

2.073 

na. 

x.  20. 

Meteorite. 

Buschof.Kurland, 

Russia. 

Grewingk  and 
Schmidt. 

Arcliiv  Nat.  Liv.-,  Ehst-, 
Kin-lands,     1804,    iii. 

3  527  1 
3.511  j 

36.011 

2.484 

7.918 

.... 

20.978 

0.709 

421-054. 

Serpentine. 

Proctorsville,  Ver- 

A. A.  Hayes. 

Proc.    Bost.    Soc.   Nat. 

36.10 

1.13 

mont. 

Jlist,  1856,  v.  340. 

G.  Wcrther. 

Scliriftcn      Kiinigsberg 

3.719 

36.25 

1.22 

31.07 

•  >  •  • 

2.61 

Gesell.,1868,ix.35-40. 

•Lherzolite. 

Pultusk,  Poland. 

•  C.  Rammelsberg. 

MOD.  Berlin.  Akad.,  1870, 

35.85 

1.96 

15.55 

3.85 

12.12 

1.56 

pp.  448-452. 

G.  vom  Rath. 

Neues  Jalir.  Min.,  1869, 

3.537-3.782 

41.54 

1.17 

11.57 

*  •  •  . 

14.04 

0.28 

pp.  80-82. 

Meteorite. 

MudJoor,  India. 

F.  Crook. 

Chem.       Const.       Met. 

30.256 

20.28 

10.091 

17.97 

0.81 

Stones,  pp  33-36. 

f  F.  Stromeyer. 

Ann.  Plivsik,  1812,  xlii. 

3.61 

36.32 

1.004 

24.415 

.... 

5574 

1.C22 

105-110. 

Meteorite. 

Erxleben,Prussia. 

<  C.  F.  Bucholz. 

Jour.    Chemie    Pliysik, 

3.5904 

30.625 

225 

13.75 

.... 

.... 

0.75 

1813,  vii.  143-174. 

M.  II.  Klaproth. 

Beitriige  Mineralkorper, 

360   ) 

35.50 

1.25 

31.00 

0.50 

1810,  vi.  303-300. 

3.64    ) 

A.  Kuhlberg. 

Arcliiv  Nat.  Liv-,  Ehst-, 

3.7:33  ) 

36324 

2.650 

10.324 

.... 

13.020 

trace. 

Kurlands,  1867(1  ),iv. 

3.721  f 

30.582 

2.385 

17.572 

.... 

12.386 

trace. 

Meteorite. 

Lixna,  Russia. 

T.  von  Grotthus. 

1-32. 
Ann.    Plivsik    Chemie, 

3.756  , 

33.20 

1.30 

26.00 

22.00 

0.50 

1852,  Ix'xxv.  577. 

A.  Laugier. 

Ann.ChimiePhys.,1824, 

3.G608 

34.00 

1.00 

.... 

.... 

40.00 

0.50 

xxv.  219-221. 

f  J.  L.  Smith. 

Am.  Jour.  Sci.,  1875  (3), 

3.57 

30.34 

0.63 

11.16 

22.28 

.... 

•Saxonite. 

Iowa  Co.,  Iowa. 

x.  302,  363. 

[  Giimbel  and  Sehwa- 

Sitz.    Miinc-hen   Akad., 

3.75 

36.08 

1.18 

10.27 

.... 

22.39 

1.39 

ger. 

1875,  v.  313-3SO. 

Meteorite. 

Nulles,     Tarrago- 

L. de  la  Escosura. 

Phil.    Mag,    1862    (4), 

3.818 

30.43 

0.84 

22.50 

13.55 

«... 

.... 

na,  Spain. 

xxiv.  530-538. 

Meteorite. 

Ohaba,     Transyl- 

F. Bukeisen. 

Sitz.  Wien  Akad.,  1858, 

3.11 

30.60 

0.28 

21.40 

.... 

1.75 

trace. 

vania. 

xxx  i.  70-84. 

Meteorite!?) 

Mainz,  Hesse. 

F.  Seelheim. 

Jahrh.    Vereins   Natur. 

3.26 

36.70 

13.49 

.... 

•  ... 

31.89 

trace. 

Nassau,      1857,      xii. 

405-410. 

Meteorite. 

Xanjemoy,  Mary- 

G. Chilton. 

Am.  Jour.  Sci.,  1825(1), 

3.0G 

36.72 

0.10 

.... 

00.30 

090 

land. 

x.  131-135. 

Meteorite. 

Hizen,  Japan. 

T.  Shimidzn. 

Trans.  Asiat.  Soc.Japan, 

3.62 

30.75 

1.89 

15.35 

.... 

8.84 

1.94 

1882,  x.  1119-203. 

{G.  Lindstrom. 

Ann.    Phvsik    Chemie, 

3.697 

36.83 

2.38 

20.08 

.... 

10.85 

2.38 

Meteorite. 

Hessle,  Sweden. 

1870,  cxli.  205-224. 

A.  E.  Nordenskjold. 

Ann    Pliysik    Chemie, 
1870,  cxli.  205-224. 

f  3  0711 
i  4.004  }• 
(  4.048  J 

36.75 
37.08 

2.00 
1.11 

1642 
16.29 

.... 

13.36 
13.49 

1  50 

2.06 

•Tufa. 

Chnntonnay,  Ven- 

C. Rammelsberg. 

Zeit.  Pent.  geol.  Gesell., 

3.44-3.49 

36.89 

2.47 

9.77 

.... 

15.99 

1.38 

dee,  France. 

1870,  xxii.  889-892. 

Meteorite. 

Blansko,  Moravia. 

J.  J.  Berzelius. 

Ann.    Physik    Chemie, 

3.40 

37.077 

2.386 

16.089 

.... 

14.945 

1.248 

ls;!4,    xxxiii.    8-25; 

1805,  cxxiv.  213-234. 

Serpentine. 

Duporth,      Corn- 

f J.  H.  Collins. 

Min.  Mag.,  1877,  i.  224. 

2.G4 

37.09 

19.90 

.... 

15.54 

2.02 

trace. 

wall,  England. 

1  J.A.Phillips. 

Min.  Mag.,  1877,  i.  224. 

286 

35.74 

12.23 

4.68 

13.84 

trace. 

*  The  prefixed  asterisk  indicates  that  the  specimen  is  a  meteorite. 


ANALYSES  OF  METEORIC  AXD  TERRESTRIAL  ROCKS. 


xxi 


Continued. 


MgO. 

MnO. 

NaA 

KA 

CrA. 

Ki. 

Co. 

Cu. 

Sn. 

P. 

S. 

HA 

Miscellaneous. 

Total. 

Si.OO 
2,1.7  t 
13.13 
14.00 
18.00 
35.03 
23.16 
2:1.77: 

1'7  171 

84.00 
23.47 
MM 
26.73 
27.483 
23.584 
23.0875 

26.50 

21.  -Hi 

10.80 
17.00 
19.70 
18.21 
19.47 
23.45 
16.12 

6.20 
MJM 
8&21 

2(5.06 
24.08 

86.16 

15.90 
2213 

2.00 
0.00 
0.409 

98.90 
100.53 
99.504 
97.00 
105.30 
100.04 
100.00 
99.999 

100.00 

90.91 
99.97 
09.39 
9901 
90.318 
99.642 

0.210 

0.24 
0.370 

0.223 

0.21 
1.23 

0.01 

NiO  —  1.17,  CoO  —  0.24,  FeS 

1.013 

2.05 
2.00 

=  3.47.    Recalculated. 

2.40 

3.50 
trace. 
2.27 
2.364 

2.184 

0.11 
0.25 
trace. 

0.002 

0.87 
0.40 
trace. 

0.225 

CrA+FeO 
0.92 

1.30 
CryoJ+Veb 

0.29 
0.158 
0.240 

CuO 

i'A 
o.oa 

0.01 
0.011 

12.04 
6.61 

OA+FeO  =  1.37. 

Cl  =  004,   NiO  =  0.20,   PA 
=  0.30. 
Loss  =  0.84. 

Grapl>ite+SnO2+loss  =0.146 

CO.2  =  17.05,    FeO+Mn+etc. 
=  3.40. 

0. 

0.02 
1.637 

0.26 

77 
0.15 
0.44 

0.325 

1.01 
0.73 

1.513 

0.17 
0.105 

trace. 



.... 

0.49 

0.705 
0.8125 

0.25 

0.025 
0.034 

0.60 
0.95 
1.34 
0.33 
0.741 

0.39 
0.285 

1.69 
2.21 
0.65 
1.162 
1.579 
0.60 

0.25 

1.725 
1.090 

2.00 
1.50 
1.30 
2.05 
1.43 

1.80 
NiO 
2.08 

ino 

4.10 

1  77 

Recalculated. 
Insol.  =  0.04.    Recalculated. 

trace 

0.87 
1  543 

.... 

2952 

FeS  =  21.625. 
S+loss  =  3.76. 

Mn  =  0.547. 
Mn  =  0.302. 

Mn  =  trace. 
Mn  =  trace. 

U,0  =  trace,  FeS  =  5.82.  Re- 
calculated. 
FeS  =  525.    Recalculated. 

FeS  =  2.34,  Insol.  =  0.79. 
FeS  =  13.14. 
Fe,  Ki  =  2.13,  FeS  =  3.80. 

Recalculated. 

NiO  =  0.30,   FeS  =  5.91,    Mn 
=  0.18. 
C  =  trace,  Cl  =  0.04. 

C  =  0.52. 
C  =  0.85. 

10000 
100.00 

99.827 
107.974 

100.20 
101.80 
98.71 
99.85 
98.20 
100.11 
100.05 

109.66 
99.01 
100.84 

100.00 
100.00 

97.09 
99.243 

99.31 
100.04 

0.680 
0.759 

trace, 
trace. 

1.00 

Cr/M-FeO 
0.759 

bass 

0.90 

CrA 
1.00 

0.120 
0.163 

2.204 
2.052 

3.50 
6.80 

.... 

0.08 

trace. 

.... 

.... 

0.25 
0.80 

0.15 

Mn. 
trace. 

1.40 
0.82 

trace. 
0.57 

0.49 
Cr2O,+FeO 
0.59 
CrA+FeO 
0.56 

0.46 

0 

V  ' 

98 
1.21 

trace 

l',o. 
0.00 

254 

1.51 

.... 

trace 

trace 

0.51 
0.42 

0.97 
0.-J4 

1.03 

0.16 

CrJi.+FeO 
0.01 

0.07 

PA 

0.34 
0.16 

trace 
trace 

1.88 

0.37 
trace. 

2  24 

.... 

1. 
2.15 

108 
2.33 

1.16 
0.8CO 

•5 
0.02 

trace, 
(race. 

0.15 
CuO-f-SnO 
0.02 

0.01 
0.02 

0.27 
0.489 

trace. 
0.98 

2.11 

n.o; 
CfjO  .+FeO 
0.616 

1. 
0.740 

trace. 
0.25 

11 
0.187 

trace. 
trace. 

0.00 

0.( 

•v—  —  "^ 

178 

".-I 
0.18 

0.050 

8.65 
1001 

XiO  =  0.207.  Analysis  reenlcu 
lated  by  Von  Uciclienbacli. 

TiO.j  =  trace. 

XX11 


A   CLASSIFIED   LIST   OF   COMPLETE   (BAUSCH) 


TABLE   IV. 


Variety. 

Locality. 

Analyst. 

Publication. 

Sp.  Gr. 

SiO-j. 

AL03. 

Fe. 

Fe.203. 

FeO. 

CaO. 

Picrite  (Pa- 

Fichtelgebirge, 

II.  Loretz. 

Grumbel's    Die    palaoli- 

37.12 

4.96 

8.92 

7.62 

0.14 

Ueopicrite). 

Bavaria. 

thisclien     Eruptivge- 

steine  des   Fichtelge- 

birges,  1874,  p  40. 

.  r  / 

Serpentine. 

Reichenstein, 

G.  L.  Ulex. 

Zeit.  Deut.  geol.Gesell., 

37.10 

1.43 

10.60 

Silesia. 

1867,  xix.  243. 

Lherzolite. 

Presque  Isle, 

3.  D.  Whitney. 

Am.Jour.  Sci.,  1859(2), 



37.25 

.... 

.... 

6.75 

14.14 



Michigan. 

xxviii.  18. 

Meteorite. 

Adare,    Limerick 

R.  Apjohn. 

Jour.  Chem.  Soc.,  1874 

3.621-4.23 

37.26 

2.03 

16.24 

.... 

8.95 

3.61 

Co.,  Ireland. 

(2),  xii.  104-106. 

Meteorite. 

Alessandria,  Pied- 

G. Missaghi. 

Ann.    Physik    Chemie, 

3.815 

37.403 

8.65 

19.37 

... 

12.831 

3.144 

mont. 

1803,  cxviii.  361-303. 

Olivinfels. 

Kalohelmen,  Nor- 

Ilanan. 

Verh.  Geol.  Reich.,1807, 

37.42 

0.10 

8.88 

way. 

pp.  71,  72. 

*Saxonite. 

GJopalpur,  India. 

A.  Exner. 

Min.   Mitth.,  1872    pp. 

37.44 

2.52 

20.96 

11.94 

1.60 

41-48. 

•Saxonite. 

Tourinnes-la- 

F.  Pisani. 

Comptes  Rendus,  1864, 

3.525 

37.47 

3.65 

11.05 

13.89 

2.61 

Grosse,    Lou- 

Iviii.  169-171. 

vain,  Belgium. 

Serpentine. 

Lynnfielcl,  Massa- 

C. T.  Jackson. 

Proc.  Bost.    Soc.    Nat. 

........ 

37.50 

.... 

•  •  *  • 



2.50 

... 

chusetts. 

Hist,  1850,  v.  318. 

Meteorite. 

Kakova,     Hun- 

E. P.  Harris. 

Chem.   Const.    Meteor- 

3.384 

37.02 

2.25 

7.11 

22.47 

0.69 

gary. 

ites,  1859,  pp.  22-34. 

Meteorite. 

Bandung,  Java. 

C.  L.  Vlaanderen. 

Comptes  Rendus,  1872, 

3.619 

37.65 

3.96 

4.96 

4.30 

16.87 

1.06 

Ixxv.  1676-1678. 

Meteorite. 

Dutulrum,  Tippe 

S.  Haughton. 

Proc.   Roy.  Soc.,   18G6, 

3.066-3.57 

37.80 

0.85 

19.57 

.... 

7.92 

1.32 

raryCo.,  Ireland. 

xv.  214-217. 

f  M.  H.  Klaproth. 

Ann.      Physik,      1809, 

3.70 

38.00 

1.00 

17.60 

25.00 

«... 

0.75 

Meteorite. 

Smolensk,  Russia. 

\ 

xxxiii.  210,  211. 

[j.  Scheerer. 

Ann.  Physik,  1808,xxix. 

3.0046 

39.00 

.... 

17.76 

17.60 



214. 

*Tufa. 

Orvinio,  Italy. 

L.  Sipiicz. 

Sitz.  Wien.  Akad.,  1875, 

(  3.675 

38.01 

2.22 

22.34 

.... 

6.55 

2.33 

Ixx.  (1),4G4. 

\  3.600 

36.82 

2.31 

22.11 



9.41 

2.31 

Meteorite. 

Pohlitz,   Reuss, 

F.  Stromeyer. 

Jonr.    Chemie    Physik, 

3.4938 

38.0574 

3.4688 

17.4896 

.... 

4.8959 

.... 

Germany. 

1810,  xxvi.  251,  252. 

Meteorite. 

Castalia,Nash  Co., 

J.  L.  Smith. 

Am.  Jour.  Sci.,  1875  (3), 

2.601t 

38.06 

2.12 

14.02 

«... 

13.10 

.... 

North  Carolina. 

x.  147,  148. 

Serpentine. 

Stanford,  Mass. 

E.  Hitchcock. 

Geol.  Mass.,  1841,  p.  ICO. 

38.09 



6.75 





Meteorite. 

Saint     Mesmin, 

F.  Pisani. 

Comptes  Rendus,  1866, 

38.10 

3.00 

4.94 

17.21 

1.09 

Aube,  France. 

Ixii.  1326. 

Meteorite. 

jhateau-Renard, 

A.  Dufre'noy. 

Comptes  Rendus,  1841. 

3.56 

38.13 

3.82 

7.70 

.... 

29.44 

0.14 

France. 

xiii.  47-53. 

f  A.  Schwager. 

Sitz.    MUnchen    Akad. 

3.4566 

38.14 

2.51 

25.70 

2.27 

Meteorite. 

Mauerkirchen, 

-j  F.  Crook. 

1878,  viii.  16-24. 
Chem.  Const.  Meteoric 

41.532 

1.705 

23.32 

2.115 

Bavaria. 

1 

Stones,  pp.  26-30. 

[  Imliof. 

Sitz.    Miinchen   Akad., 

3.452 

25.40 

.... 

2.33 

40.24 

.... 

.... 

1878,  viii.  17. 

Serpentine. 

Varzi,  Italy. 

A.  Cossa. 

Ric.  Chin).  Roc.  Italia, 

38.22 

trace. 

14.05 

trace. 

1881.  pp.  162-164. 

Serpentine. 

[vynance  Cove, 

S.  Ilaughton. 

Phil.  Mag.,  1855  (4),  x. 

38.29 

13.50 

Cornwall,  Eng. 

254. 

Meteorite. 

Charsonville,  Loi- 

L.  N.  Vauquelin. 

Ann.   Mus.   Hist.   Nat., 

3.712 

38.40 

3.60 

25.80 

.... 

.... 

4.20 

ret,  France. 

1811,  xvii.  1-15. 

3.57-3.65 

Meteorite. 

Drake's  Creek, 

f  E.  II.  Baumhauer 

Ann.    Plivsik.   Chemie, 

3.469 

38.503 

4.807 

12.816 

.... 

10.029 

0.70 

Simmer   Co., 

| 

1845,  Ixvi,  408-503. 

Tennessee. 

[  H.  Seybert. 

Am.Jour.  Sci.,  1830(1), 

3.484-3.487 

40.00 

2.466 

12.00 



12.20 

.... 

xvii.  326-328. 

Meteorite. 

Aukoma    (Pillits- 

Grewingk   and 

Archiv  Nat.  Liv-,  Ehst-, 

3.647 

38.593 

2.491 

25.667 

.... 

2.519 

0.48 

fer),       Livland, 

Schmidt. 

Knrlands,     1804,    iii. 

Russia. 

421-554. 

*Saxonite. 

Waconda.Kansas. 

J.  L.  Smith. 

Am.Jour.  Sci.,  1877  (3), 

3.40-3.60 

38.61 

1.09 

4.60 

22.81 

trace. 

xiii.  211-213. 

Serpentine. 

Monteferrato, 

A.  Cossa. 

Ric.  Chim.  Roc.  Italia, 

2.55 

38.70 

0.58 

.... 

3.19 

7.20 

trace. 

Italy. 

1881,  pp.  148,  140. 

Meteorite. 

Richmond,    Vir- 

C. Rammelsberg. 

Mon.      Berlin.     Akad., 

3.3713 

38.71 

2.17 

6.45 

.... 

18.17 

2.53 

ginia. 

1870,  pp.  453-457. 

Meteorite. 

Ausso  n,  Haute  Ga- 

f  A.  A.  Damour. 

Comptes  Rendus,  1859, 

3.51-3.57 

38.72 

1.85 

8.63 



16.93 

0.80 

ronne,  France. 

JE.  P.  Harris. 

xlix.  ;il-:;<>. 
Chem.    Const.    Meteor- 

3.50 

38.46 

2.25 

7.13 

18.00 

trace. 

ites,  1859,  pp.  44-51. 

The  prefixed  asterisk  indicates  that  the  specimen  is  a  meteorite. 


ANALYSES  OF  METEORIC  AND  TERRESTRIAL  EOCKS. 


xxin 


Continued. 


MgO. 

MnO. 

Na/>. 

K/>. 

CrA- 

Ni. 

Co. 

Cn. 

Sn. 

P. 

S. 

HoO. 

Miscellaneous. 

Total. 

::I;LM 

ll.lTii 
<&22 
tt.72 

24.10 

41.00 
21.74 
13.24 

1'::.:::; 
14.25 
20.00 

24.11 
il.60 

29.9300 
H.48 

40.19 
2.1.IU 
17.07 
21.7:: 
24.202 
28.75 
32.83 
34.24 
18.60 

88.833 

•j:;.r,r,ii 

25.15 
H  H 
27.:M> 
82.68 
26.06 

0.40 

0.40 

0.49 

!'•/>« 
0.10 

5.04 

12.15 
10.89 

TiO2  =  0.40,  CCX,  =  0.09. 

FeA»  =  2.70. 

Analysis    of    soluble    portion 
only. 
FeS  =  0.54,  V  =  trace.      Re- 
calculated. 

98.00 

100.34 
98.80 
90.19 

08.327 
99.73 
98.90 
99.72 

100.00 
101.13 
98.33 
98.99 
100.00 
100.00 

101.42 
100.96 

99.1802 
98.92 
100.00 
99.00 
99.97 
100.75 
98.430 
100.00 
99.76 
98.12 
98.70 
100.00 
95.931 
100.00 

98.38 
99.70 
98.16 
99.05 
98.01 

1  10 

&BO 

Mil 
tract'. 

(U7 
0.20 
trace. 

0.79 

0.12 

in'  -i-FeO 
"1.75 

0.845 

2.73 

1.077 
NiO 
OJ8S 

1.80 
1.30 

0.10 
trace. 

3.831 

Ignition  =  4.71. 

0.62 

0.21 

trace. 
Cr2O3+FeO 
0.71 

0.10 

1  74 

017 

2.21 

2.: 

A 

15.CO 

CaC03  =  4.00. 
Graphite  =  0.14.  Recalculated. 

0.42 
0.16 

1.76 
2.11 
0.96 

061 
1.07 
0.50 

Cr.2Os+FeO 
0.07 
(>.,(),  +FeO 
4.41 
Cr.jO8+FeO 
1.50 

1.24 
1.03 
1.03 
0.40 
1.25 

2.15 
3.04 

1.3057 
1.12 

0.10 
0.14 

trace. 

.... 

0.01 

trace. 
2  13 

FeS  =  4.05.     Recalculated. 
Loss,  etc.  =  3.00. 
Loss,  etc.  =  4.50. 

1.1  407 

1.46 
0.90 

0.55 

0.31 
0.20 

trace. 

0.1298 

1.94 

2.04 
2.6957 
0.46 

- 

0.06 

trace. 

.... 

trace. 

14.77 

Li/)  =  trace. 
Loss  =  0.  20. 
FeS  =  2.09. 

.... 

Crj68+FeO 
2.18 

0.89 

CraO.,+FeO 
0,725 

8. 
0.80 
1.00 
0.242 

13 
0.27 
0.48 

0.145 

1.65 

0.39 
209 
0.705 

0.14 

.... 

Fe+Ni  =  0.30. 
Fe+Xi=  3.745. 
S+loss  =  2.08. 

1.20 

trace. 

1405 

1209 

MM 
0.00 

2.31 

0.594 

0.025 

0 
1.50 

1.374 
0.833 
0487 

0.00 

1.405 
NIO 

2.100 

1.878 

0.04 
MO 
trace. 

1.18 
0.00 
1.02 

5.00 

1.804 
2433 

0.102 

1  V 

O.C 

s 

<55 

.... 

.... 

CuO+SnO2+KiO  =  2.528. 

0.018 

Mn 
0.46 

0.341 
1.07 

0.24 

trace. 

trace. 
0.10 

0.013 
trace. 

3.492 

Graphite+TiO^+Ioss  =0.115. 

Li./)  =  trace,  FeS  =  3.85.  Re- 
calculated. 
Ignition  =  13.23. 

trace. 

.... 

0.30 

trace. 
0.34 

0.57 
0.10 

0.11 
0.18 

Cr.,Oa+Fc<> 

Cr.,0, 
0.78 

p+Fe+Ni,  etc.  =  2.00,  FeS  = 
374.     Keualriilalcd. 
FeS  =2.51.     Recalculated. 

V 

0.00 

.... 

.... 

trace. 

2.10 

t  Probably  a  misprint  for  3.001. 


XXIV 


A  CLASSIFIED   LIST   OF   COMPLETE   (BAUSCH) 


TABLE   IV. 


Variety. 

Locality. 

Analyst. 

Publication. 

Sp.  Gr. 

SiO2. 

Al,0., 

Fe. 

Fe.203. 

FeO. 

CaO. 

Meteorite. 

Ausson,  Haute  Ga- 

Filhol and  Leyme- 

Comptes  Rendus,  1859, 

3.30 

60.28 

1.82 

8.30 

2.32 

15.38 

0.55 

ronne,  France. 

rie. 

xlviii.  193-198. 

Fieri  te. 

Schiinau,    Neutit- 

F.  E.  Szameit. 

Sitz.  Wien.  Acad.,  1800, 

3.029 

38.72 

10.19 

6.30 

6.14 

10.37 

schein,  Moravia. 

liii.  (1),260. 

Serpentine. 

Neurode,  Silesia. 

G.  vom  Rath. 

Ann.   1'hvsik    Chemie, 

2.912 

38.78 

3.06 

.... 

14.19 



4.51 

1855,  cxv.  553. 

Serpentine. 

Kiver  Oisain,  Ti- 

Pufahl. 

Saminl.  (ieol.  Mus.  Lei- 

38.81 

1.14 

6.80 

2.10 

0.32 

mor. 

den,  1884,  ii.  109. 

Serpentine. 

Lizard.  Cornwall, 
England. 

J.  A.  Phillips. 

Phil.    Mag.,    1871    (4), 
xli.  101. 

2.59    j 

38.86 
38.58 

2.95 
3.06 

1.86 
1.95 

5.04 
6.10 

trace, 
trace. 

Meteorite. 

Rakowska,   Tula, 

P.  Grigoriew. 

Zeit.  Dent.  geol.  Oesell., 

3.582 

38.87 

2.66 

6.67 



1:5.44 

2.36 

Russia. 

1880,  xxxii.  417-420. 

Dunite. 

Sum)  more.     Nor- 

W. C.  Brogger. 

Neues  Jalir.  Min.,  1880, 

3.32 

38.87 

8.45 

0.99 

way. 

ii.  187-192. 

Picrite. 

Soldo",     Neutit- 

G.  Tschermak. 

Sitz.  Wien.  Akad.,  1806, 

2.901 

38.90 

10.30 

.. 

4.90 

7.00 

6.00 

schein,  Moravia. 

liii.    (1),   263;     1807, 

Ivi.  274,  276. 

Serpentine. 

1'rato,  Italy. 

A.  Cossa. 

Ric.  Cliim.  Roc.  Italia, 

2.57-2.69 

38.94 

.... 

1.18 

8.25 

trace. 

1881,  pp.  151,  152. 

. 

f  C.  Rammelsberg. 

Mon.  Berlin.  Akad.,1870, 

38.90 

2.00 

13.51 

14.52 

1.18 

Meteorite. 

Linn  Co.,  Iowa. 

pp.  457-45U. 

1  C.  U.  Shepard. 

Am.,  lour.  Sci.,  1848  (2), 

62.34 

8.98 

20.42 

vi.  403-405. 

Meteorite. 

Cynthiana,    Ken- 

J. L.  Smith. 

Am.  Jour.  Sci.,  1877  (3), 

3.41 

38.99 

0.22 

5.36 

.... 

19.73 

2.20 

tucky. 

xiv.  224-227. 

*Buchnerite. 

Alfianrllo,  Bres- 

H. von  Foullon. 

Sitz.  Wien.  Akad.,  1883, 

39.14 

0.93 

11.81 

17.42 

1.96 

cia,  Italy. 

Ixxxviii.  (1),433. 

Meteorite. 

Sc'tif,  Algeria.  • 

S.  Meunier. 

Cornples  Hendus,  1808, 

3.595 

39.20 

1.64 

14.18 

2.06 

Ixvi.  513-519. 

Serpentine. 

Rio  Marina,  Ell>a. 

A.  Cossa. 

Uic.  Chim.  Roc.  Italia, 

2.59 

39.21 

trace. 

.... 

7.87 

2.63 

trace. 

1881,  pp.  134.  135. 

Meteorite. 

Utreclit,  Holland. 

E.  H.  Baumhauer. 

Ann.    Pliysik    Chemie, 

3.57-3.05 

39.301 

2.252 

11.068 

.... 

15.290 

1.48 

1845,  Ixvi.  405-498. 

Serpentine. 

Longone,  Elba. 

A.  Cossa. 

Ric.  Chim.  Roe.  Italia, 

2.G1 

39.38 

trace. 

.... 

8.26 

3.67 

trace. 

1881,  pp.  130,  137. 

Meteorite. 

Parnallee,  India. 

E.  Pfeitfer. 

Sitz.  Wien.  Akad.,  1863, 

3.115 

39.408 

2.573 

9.83 

.... 

15.283 

0.56 

xlvii.  (2),  400-403. 

Serpentine. 

Rio  Alto,  Elba. 

A.  Cossa. 

Rie.  Chim.  Roc.  Italia, 

2.01 

39.68 

«... 

*  >  •  . 

7.65 

4.13 

trace. 

1881,  pp.  135.  13(i. 

Dunite. 

Karlstatten,  Aus- 

Kouya. 

Sitz.  Wien.  Akad.,  1867, 

3.011 

39.61 

1.68 

8.42 

trace. 

tria. 

Ivi.  277. 

Meteorite. 

Honolulu,  Hawaii, 
Sandwich  Isls. 

A.  Kuhlberg. 

Archiv  Nat.  Liv  ,  Ehst-, 
Kurlnn.ls,    1867    (1), 

3.5309  I 
3.3964  ) 

39.65 

1.93 

6.45 



19.15 



iv.  1-32. 

Meteorite. 

Villeneuve,   Ales- 

Bertolio. 

Comptes  Rendus,  1808, 

3.29 

39.601 

0.416 

20.70 

.... 

12.234 

0.878 

sandria,  Italy. 

Ixvii.  322-320. 

Meteorite. 

Girgcnti,  Sicily. 

G.  vom  Rath. 

Ann.    Physik    Chemie, 

3.594 

39.72 

"1.44 

10.40 

.... 

16.47 

1.70 

1869,cxxxviii.541-545. 

Serpentine. 

Valle    Tonrnnn- 

A.  Cossa. 

Ric.  Cliim.  Roc.  Italia, 

2.80 

39.76 

.... 

5.11 

6.37 

.... 

elie,  Piedmont. 

1881.  p.  120. 

Serpentine. 

MontemezEano, 

A.  Cossa. 

Ric.  Chim.  Roc.  Italia, 

2.56; 

39.77 

trace. 

1.76 

8.48 

trace. 

Italy. 

1881.  p.  150. 

Olivinfels. 

Krauhat,  Steier- 

H.  Wieser. 

Min.  Mitth.,  1872,  p.  79. 

2.889 

39.87 

0.§9 

.... 

9.76 

0.64 

0.44 

inark. 

Serpentine. 

Portoferraio, 

A.  Cossa. 

Ric.  Chim.  Roc.  Italia, 

2.53 

39.932 

trace. 

.... 

6.899 

3.75 

.... 

Elba. 

1881,  pp.  137,  138. 

Meteorite. 

Swajalm,    Kur- 
land,  Russia. 

A.  Kuhlberg. 

Archiv  Nat.  Liv-,  Ehst-. 
Kurlanils,18G7(l),iv. 

3.4341  | 

39.97 
40.414 

3.06 
3.798 

6.15 
8.322 



ia45 
15.424 



1-32. 

Meteorite. 

Xerft,  Russia. 

A.  Kuhlberg. 

Ann.    Pliysik    Chemie, 

40.00 

3.52 

8.36 

15.98 

0.05 

18(19,  rxxxvi.  448,441). 

Meteorite. 

Pohgel,    Kurland. 
Russia. 

A.  Kuhlberg. 

Archiv  Nat.  Liv-,  Ehst-, 
Kurlands,    1867    (1), 

3.555  j 

40.05 
39.556 

3.94 
3.299 

10.15 

8.835 



14.11 

14.902 

trace. 
0.185 

iv.  1-32. 

Serpentine 

Ballinahinch 

J.  A.  Galbraith. 

Jour.  Ot'ol  Soc.  Dublin, 

40.12 

trace. 

3.47 

trace. 

Quarry,  Conne- 

1852,  v.  138. 

mara,  Ireland. 

Meteorite. 

Schonenber^,  lia- 

C.  W.  Giimbel. 

Sitz.   Miinchen    Akad., 

40.13 

6.57 

13.77 

17.12 

2.31 

varia. 

1878,  viii.  40-40. 

Meteorite. 

Sokol  IJanja,  Ser- 

S.  M.  Losanitch. 

Beriehte  Chem.  Gesell. 

3.502 

40.14 

•  .  •  . 

5.82 

.... 

25.54 

.... 

via. 

Berlin,  1878,  xi.9U-98. 

*  The  prefixed  asterisk  indicates  that  the  specimen  is  a  meteorite. 


ANALYSES   OF  METEORIC   AND  TERRESTRIAL  ROCKS. 


XXV 


'nued. 


KgO. 

Mud. 

Na.O. 

KM 

CrjOj. 

Ni. 

Co. 

Cu. 

Sn. 

P. 

S. 

H.p. 

Miscellaneous. 

Total. 

1(171 

2.10 

0.72 

1.82 

Recalculated. 

no.,  =  trace,  CO.,  =  2.93,  Or- 
ganic material  =  truce. 
Ignition  =  7.74. 

Ti0.2  =  0.16. 

99.73 
100.27 
99.55 
99.92 

1(IO.:!0 
D'J.'.I? 

1R60 

8101 
MJU 

24.GO 
61.80 
KXSO 

26.05 
175 

2G.5G 
25.01 
25.08 
36.92 
24.066 

Kuoa 

22.81U 
36.37 

42.2'.l 

24.51 

14.778 

24.61 
38.10 

:;:,•;:; 
40.09 

24.!>1 
96.481 

25.59 

84.85 
10.681 

40.04 

10.81 
2578 

1  50 

167 

3.96 

O.'JO 
trace. 

tttliv. 

trace. 
0.24 
0.12 

0.11 
0.12 

0.77 
0.78 

2.04 

049 

trace. 

0.33 
O.SO 

0.37 

0.02 

0.08 
0.08 
Crf>s+yM 
0.81 

Cu() 
0.04 

1U), 

o.oa 

14.87 

15.52 
15.52 

HtO 
0.88 

O.-.M 

1.43 

0.32 

0.12 

Mn  =  trace,  C  =  0.13,  FeS  = 
0.10. 

100.29 
99.10 

99.84 
100.00 
98.21 
101.77 
100.42 
99.84 
99.44 
100.00 
99.78 
100.00 
100.45 
97.92 

98.09 

100.00 
98.45 
99.72 
09.71 
100.11 
100.036 

98.30 
B&368 

99.40 

!*  » 

98.811 
98.99 

100.00 
100.21 

1.30 

0.80 

4.50 

CO.2=1.80. 

Ignition  =  13.90. 
Recalculated. 
FeS  =  6.00.    Recalculated. 
FeS  =  5.60.    Becalculated. 

0.29 

mo 

truce. 
1.08 
1.46 
0.60 
1.09 

• 

•  • 

0.38 

trace. 

2.32 

0. 
0.49 
075 

20 
010 

0.15 

0.07 

2.71 

0.12 
0.27 
0.650 

trace. 
CraOa+FeO 
trace. 

trace. 

Fe+Ni  =  8.32,  FeS  =  8.04. 
Ignition  =  12.64. 

MnO  +  NiO  =  0.009,     CuO  + 
SnO.,  =  0.2.")li. 
TiOi  =  trace,  Ignition  =  12.85. 

CoO.,  =  0.00,  Zn  =  trace,  NiO 
="0.724. 
Ignition  =  12.72. 

trace. 

trace. 
0.54 

trace.'. 

1.395 
1.907 
001 

0.152 
0.547 
0.02 

26 

0.005 

1.897 

1.24 

2 

O.C 

0.904 

0.00 

trace. 

trace. 

0.10 

2.712 

0.684 

589 

Mn. 
0.21 

trace. 

0.88" 

trace. 

CrjOj+FeO 
1.35 

0.088 

Cr-Og+FeO 
1.00 

trace. 
0.27 

0.04 

I'.O, 
O.iV.17 

2.29 

0.503 
2.06 

1.0£ 

NiO 

6.371 

1.05 
NiO 

trace. 

.... 

trace. 

996 

Cl  =  0.105,  Loss  =  0.537. 
Recalculated. 

4.1 

51 

Ignition  =  12.10. 

trace, 
trace. 

trace. 
.0.045 

0.03 

0.04 
0.021 

1.28 

NiO 
0.00 

648 

0.183 
Cr.,O,-(-FeO 

"  o.i;j 
0.478 
Cr./);1+FeO 
0.05 
Cr.,O,-l-FeO 
0.68 
0.848 

TiO,=  trace,  Ignition=13.047 

Mn  =  0.05. 
Mn  =  0  08. 

Mn  =  0.10. 

Mn  =  0.09. 
Mn  =  0.107. 

CO.,  =  2.00. 

0.84 
0.668 

1.C5 

0.766 

0.030 

0.09 
0.038 

0.08 

0.123 
0.072 



.... 

0.01 
0.005 

0.05 

0.06 

(».0.-|! 

1.88 
1.293 

2.02 

2.35 
2.M6 

13.3<; 

1.4t 
U 

1.32 

.5 
trace. 

.... 

rs 

0.9* 

1 

0.12 

2.20 
0.26 

0.73 
0.06 

0.60 
0.04 

1.47 
0.92 

0.30 
trace. 

1.93 
1.40 

0.07 

.... 

Recalculated. 

XXVI 


A  CLASSIFIED   LIST   OF   COMPLETE   (BAUSCH) 


TABLE   IV. 


Variety. 

Locality. 

Analyst. 

Publication. 

Sp.  Gr. 

Si0.2. 

A1A- 

Fe. 

Fe.203. 

FeO. 

CaO. 

Meteorite. 

Bachmut,     Jeka- 
therinoslaw, 

f  A.  Kublberg. 

1 

iF.  T.  Giese. 

Arcbiv  Nat.  Liv-,  Ebst-, 
Kurlands,    18(57    (1), 
iv.  1-32. 
Ann.    Pbysik,   1815,   1. 

3.563  | 
3.4235 

40.209 
38.971 

44.00 

2.884 
2.6W 

3.00 

8.105 
8.928 

21.00 

.... 

22.374 
16.288 

0.089 

trace. 

Russia. 

F.  Wohler. 

117,  118. 
Sitz.  Wien.  Akad.  1802 

3371 

2.78 

12.00 

14.17 

1  "1 

*Buchnerite. 

Tiescliitz,  Mora- 
via. 
Fohrenbiihl,  Ba- 

J. Habermann. 
G.  Schulze. 

xlvi.  (2),  M02-306. 
Denks.    Wien.    Akad., 
1879,  xxxix.  187-201. 
Zeit.  Deut.  geol.  Gesell., 

3.59 

40.23 
40.30 

1.93 
1.30 

10.26 

1.35 

19.48 

8.50 

1.54 

trace. 

varia. 

T.  S.  Hunt. 

1883,  xxxv.  451. 
Am.  Jour    Sci.j    1858 

2.597 

4030 

7.02 

*Saxonite. 
Picrite. 
Serpentine. 
Serpentine. 

Goalpara,  India. 

Diltenburg,    Nas- 
sau, 
leiligenblut,   Ca- 
rintliia. 
Lizard  Point, 

N.  Teclu. 
G.  Angelbis. 
R.  v.  Drasehe. 
T.  S.  Hunt. 

xxv.  219. 
Sitz.  Wien.  Akad.,  1870, 
Ixii.  (2),  852-864. 
[naug.  Dissert.,   Bonn, 
1877,  p.  9. 
Min.  Mitth.,  1871,  p.  '8. 

Am.   Jour.    Sci.,   1858, 

3.444 
3.108 
2.79 

40.36 
40.37 
40.39 
40.40 

9.86 
1.68 
0.65 

8.49 

4.76 
9.98 

13.32 
8.34 
3.32 

0.60 
4.74 
4.78 

Serpentine. 
Serpentine. 
Meteorite. 

Serpentine. 
Serpentine. 

Cornwall. 
?avaro,Piedmont. 

..evanto,  Italy. 

)oroninsk,    Sibe- 
ria. 

Fahlun,  Sweden. 
Sprechenstein, 

A.  Cossa. 
C.  T.  Heycock. 
J.  Sclieerer. 

{R.  F.  Marchand. 
J.  L.  Jordan. 
E.  Hussak. 

xxvi.  239. 
Sic.  Cbim.  Roc.  Italia, 
1881,  pp.  125-127. 
Geol.    Mag.,   187'J  (2), 
vi.  307. 
Mem.  Acad.  St.  Pe'ters- 
bourg,     1813-14,   vi., 
Hist.,  p.  46. 
Neues  Jahr.  Min.,  1845, 
p.  831. 
S'eues  Jalir.  Min.,  1845 
p.  831. 
Min.   Mitth.,   1882  (2), 

2.66 
2.705 
36154 

2.63 

40.43 
40.47 
40.50 

40.52 
40.32 
40.55 

trace. 
4.35 
3.25 

0.21 
2.70 

.... 

9.55 

7. 
18.50 

10.40 

4.23 
31 

3.01 
3.33 

3.51 

0.84 
6.25 

4.40 

Meteorite. 
Meteorite. 
Picrite. 
Serpentine. 

Tyrol, 
lochester,     Indi- 
ana. 
)hurmsalla, 
India. 
Freiberg,    Neutit- 
schein,  Moravia. 
Talof    Copper 
Mine,   Ural. 

J.  L.  Smith. 
S.  Hanghton. 
P.  Jubasz. 
Ivanoff. 
H  Hofer. 

v.  67. 
Am.  Jour.  Sei.,  1877  (3) 
xiv.  219-222. 
Proc.  Roy.  Soc.,  1866 
xv.  214-217. 
Sitz.  Wien.  Akad.,  1866, 
liii.  (1),  265. 
Neues  Jahr.  Min.,  1847 
p.  207. 
Jabrb.     Geol.    Reichs. 

3.55 
3.399 
2.96 
2.65 

40.61 
40.69 
40.79 
40.80 
40.81 

0.10 
0.60. 
10.41 
3.02 
1.09 

0.45 
6.88 

3.62 
1.98 

16.56 
11.20 
6.39 
2.20 
6.02 

2.41 

8.48 
0.42 
1.32 

Austria. 

1866,  xvi.  443-446. 
Ann    Mines     1850   (4) 

2.749 

40.83 

0.92 

7.39 

1.50 

Serpentine. 

Vosgcs,  France. 
Corio,    Piedmont. 

A.  Cossa. 

xviii.  :!41. 
Ric.  Cliim.  Roc.  Italia 
1881,  pp.  123,  124. 

2.64 

(2.587  ) 

40.88 
4090 

trace. 

.... 

2.05 

10.21 
4.70 

trace. 
0.02 

1881   pp   115-118 

J  2.500  > 

4086 

4.59 

O.OS 

E  Hussak. 

Min.   Mitth.,  1882   (2) 

(  2.546  ) 

40.90 

2.08 

7.68 

0.30 

Tyrol. 

v.  70. 

41.00 

0.75 

45.00 

2.00 

Meteorite. 
Serpentine. 

bynia,  Russia. 
Searsmont,Maine 

Heiligenblut,  Ca 
rinthia. 

J.  L.  Smith. 
R.  von  Drasche. 
f  Keller 

1824,  xxv.  219-221. 
Am.  Jour.  Sci.,  1871  (3) 
ii.  200,  201. 
Min.  Mitth.,  1871,  p.  9. 

3.701 
2.91 

41.04 
41.05 
41.12 

0.86 
1.67 
3.22 

13.16 
1037 

8.82 

13.84 
3.15 
17.42 

3.76 
2.06 

Meteorite. 

Kralienberg,    Ba 
varia. 

1878,  viii.  47-58. 

39.08 

2.08 

4.43 

28.53 

13.35 

Dunite. 
Serpentine. 

Meteorite. 

Bonbomme,  Vos 
ges,  France. 
Neurode,  Silesia. 

Stewart   Co., 
Georgia. 

B.  Weigand. 
Fickler. 
J.  L.  Smith. 

1878,  viii.  47-58. 
Min.  Mitth.,  1875,  p.  187 

Sitz.  Wien.  Akad.,  1867 
Ivi.  274,  275. 
Am.  Jour.  Sci.,  1870  (2) 
1.  339-341. 
Phil    Mag     1855  (4)   x 

2.88 
3.65 

41.13 
41.13 
41.15 
41.24 

0.84 

13.56 
2.17 

6.09 

3.86 

2.77 
6.19 
14.85 
7.41 

trace. 
0.72 
0.04 

Villa  Rota  Italy 

364. 

Ann    Mines    1848  (4) 

2.644 

41.34 

3.22 

6.54 

xiv.  79. 

The  prefixed  asterisk  indicates  that  the  specimen  is  a  meteorite. 


ANALYSES   OF   METEORIC   AND   TERRESTRIAL  ROCKS. 


XXVll 


KgO. 

MnO. 

NajO. 

K.,0. 

CrJ)a. 

Ni. 

Co. 

Cu. 

Sn. 

P. 

S. 

HoO 

Miscellaneous. 

Total. 

20.11.". 

ou:;r, 

0.519 

trace. 

Cr,03+FeO 

(Mill 

1.191 

' 

0.042 

2.516 

Mn  —  0.228. 

llS.ltt! 

"11  (!•'." 

ll.nl/, 

0.734 

0.988 

1  20; 

t 

0.061 

2.221 

Mn  —  0.185. 

!)7  7^2 

2.50 

S+Cr..O3  —  1.00,  Mn  —  1  .00. 

90.50 

27  :::', 

1.03 

0.45 

0.13 

2.00 

1.01 

1 

0.02 

1.81 

Mn  —  1.00.      Recalculated  b\ 

98.70 

"I  )  .',."> 

1.53 

131 

1'A 

022 

1  66 

A.  Kulilberg. 

0902 

31.21 

0.90 

13.00 

99.66 

;;'.HI7 

Nil) 

1336 

100.00 

8746 

C  —  0.72,  II  —  0.13.     Recalcu 

101.08 

"1  (i:; 

361 

082 

504 

lated  by  Tescliernmk. 

9977 

9.86 

100.13 

87.43 

OjOg+FeO 

"747 

NiO 
0.16 

Ignition  —  13  90. 

100.00 

31.82 

trace. 

HIO 

0.06 

10.05 

100.25 

34.69 

0.15 

NiO 
0.49 

H2O+FeS—  1161. 

100.11 

9.00 

1.25 

2.00 

10.00 

8.12 

Loss  —  1.13. 

100.00 

42.05 

13.85 

C  —  0.30. 

99.94 

41.70 

1354 

98.95 

BUM 

9.32 

100.96 

28.73 

0.67 

0.05 

0.42 

005 

FeS  —  3.00.     Recalculated. 

101.85 

26.59 

1.21; 

0.39 

0.21 

Cr2O8+FeO 
"4.16 

1.54 

FeS  —  6  61.    Recalculated. 

90.14 

2::.::  I 

1.71 

0.71 

404 

CO2  —  trace 

9939 

40.50 

0.20 

1202 

99.24 

37.1  1'j 

0.01 

0.32 

10.26 

98.53 

37.98 

trace. 

0.68 

Ignition  —  10  70. 

100.00 

34.H4 

trace. 

Nil) 
051 

11  74 

98.02 

41.31 

trace. 

0.02 

NiO 
0.08 

1'A 

1340 

100.43 

41.87 

trace. 

0.03 

0.09 

1308 

100.05 

37.40 

12  16 

100.56 

14.90 

Mn 
trace. 

0.75 

1.00 

400 

109.40 

26.10 
88.70 

V  . 

0. 

,  ' 

50 

Undt. 

ISO 

0.06 

Undt. 

.... 

Undt. 

.... 

L,i2O  =  trace.    Recalculated. 

98.61 
100.60 

18.02 

0.78 

0.17 

1.22 

0.89 

UK 

BnOJ 

0  18" 

046 

235 

100.82 

5.97 

0.82 

1.81 

1.48 

0.39 

1  31 

99.26 

41.88 

trace. 

trace. 

trace. 

trace. 

Nil) 

100.60 

22.52 

0.98 

0.83 

Cr.,03+FeO 
"2.1'J 

8.30 

1112.40 

28.13 

1.00 

trace. 

0.85 

0.05 

FeS  —  6.10  L1..O  —  trace.    Re- 

100.59 

30.28 

14  16 

calculated. 

09.09 

37.01 

trace. 

trace. 

1206 

99.67 

XXVlll 


A   CLASSIFIED   LIST   OF   COMPLETE   (BAUSCH) 


TABLE   IV. 


Variety. 

Locality. 

Analyst. 

Publication. 

Sp.  Gr. 

Si02. 

AL2Oa. 

Fe. 

Fe,03. 

FeO. 

CaO. 

Picrite. 
Serpentine. 
Serpentine. 
Dunite. 

Schriesheim,  Ba- 
den. 
Hillswick      Ness, 
Scotland. 
Windiseli-Matrey, 
Tyrol. 
Franklin,    Macon 

C.  W.  C.  Fuchs. 
M.  F.  Heddle. 
It.  v.  Drasehe. 
T.  M.  Chatard. 

Neues  Jahr.  Min.,  1804, 
pp.  820-332. 
Min.  Mag.,  1880,  iii.  21. 

Min.  Mitth.,  1871,  p.  4. 
Geol.    North    Carolina, 

2.82 
2.522 
2.69 

41.44 
41.46 
41.57 
41.58 

6.63 
0.01 
0.67 
0.14 

:: 

13.87 
2.422 
2.63 

6.30 

i.iea 

5.31 
7.49 

7.20 
trace. 
1.22 
0.11 

Meteorite. 

Co.,  N.  C. 

Mezo-Madaras, 
Transylvania. 

f  Woliler  and  Atkin- 
<      son. 
(  C.  Rammelsberg. 

1881,  p.  42. 
Phil.  Mag.,  1856  (4),xi. 
141-143. 

3.50 

41.62 
37.64 

3.15 
3.41 

18.10 
12.12 

.... 

4.61 
1544 

1.80 
1  08 

Serpentine. 

Kuhstein      Bava- 

G. Schulze. 

1871,  xxiii.  734-737. 
Zeit   l)eut  geol  Gesell 

41.63 

1.46 

385 

467 

3  57 

Lherzolite. 
Serpentine. 

ria. 
Germagnano, 
Piedmont. 
Dillenburg,  Prus- 

A. Cossa. 
C.  Schnabel. 

1883,  xxxv.  447. 
Ric.  ('him.  Roc.  Italia, 
1881,  pp.  112,  113. 

3.116 

41.06 
41.70 

4.25 
7.04 

.... 

2.95 

10.38 
26.95 

1.76 
3  '-'A 

Serpentine. 
Meteorite. 

sia. 

Malenker    Thai, 
Graubiindten. 

L.  R.  v.  Fellenberg. 

worterbuch,  4,  Supp., 
1847,  p.  200. 
Neues  Jahr.  Min.,  1867, 
p.  197. 
Ann  CbimiePhys  18°7 

2.99 
3.2442 

41.72 
41  75 

3.19 

.... 

4300 

7.06 

Meteorite. 
Dunite. 

Lherzolite. 

llaly. 
Krahenberg,    Ba- 
varia. 

Webster,  Jackson 
Co.,  N.  C. 

Mohsdorf,    Sax- 

G. vom  Rath. 
F.  A.  Genth. 

Leuckart. 

xxxiv.  139-142. 
Ann.    Physik    Cbemie, 
1869,cxxxvii.328-336. 

Am.Jour.  Sci.,  1862(2), 
xxxiii.  199-203. 

Neues  Jahr   Min    1876 

3.4975 
(3.28 
I  3.252 

41.78 
41.89 
40.74 
41.99 

0.06 
trace, 
trace. 
6.734 

6.31 

9.143 

19.53 
7.39 
7.2C 
1.659 

1.94 
0.08 
0.02 
1.841 

Serpentine. 
Meteorite. 

•Lherzolite. 

ony. 
Radau,  Ilarz. 

Guernsey  Co., 
Ohio. 

New    Concord, 
Ohio. 

A.  Streng. 
J.  L.  Smith, 
f  J.  L.  Smith. 
•  D.  M.  Johnson. 

pp.  232,  233. 
Neues  Jahr.  Min.,  1862, 
p.  540. 
Am.  Jour.  Sci.,  1861  (2), 
xxxi.  87-98. 
Am.Jour.  Sci,  1861  (2), 
xxxi.  87-98. 
Am.  Jour.  Sc-i.,  1860  (2), 
xxx.  109-111. 

2.88  ' 
3.55 
3.55 
3.5417 

42.02 
42.24 
42.25 
51.25 
40.391 

13.89 
0.28 
0.28 
5.325 
2.30 

9.31 
9.309 
8.803 

5.778 

5.819 

3.19 
25.03 
25.03 
25.204 
18.133 

8.01 
0.02 
0.018 

0.785 
2.523 

Serpentine. 

Goujot,     Vosges, 

A.  Delesse. 

1863,  p.  105. 
Ann.   Mines,    1850  (4) 

42.26 

1.51 

7.11 

0.80 

Serpentine. 

France. 
Poldnewnja,  Rus- 

A A.  Loseh. 

xviii.  342. 
Zeit.    Kryst.,    1881,    v. 

42.34 

1.68 

0.29 

1.98 

Lhcrzolite. 

sia. 

F  Kohler. 

591. 
Neues  Jahr  Min    1862 

2668 

42.36 

2.18 

0.03 

Meteorite. 

Middlesborougb, 

AV.  Flight. 

p.  541. 
Phil.  Trans.    1882,  pp 

42.39 

1.73 

7.30 

23.76 

Yorkshire,  Kng. 

896-899. 

f 

4253 

2.22 

V  Merz 

4227 

1.88 

sell*  Xuricli   1861   vi 

4244 

1.80 

369-372 

i 

4245 

2.12 

42  13 

2.23 

Lherzolite. 
•Lherzolite. 

Sehillerfels. 

Germa<inano, 
Piedmont. 
Mocs,  Transylva- 
nia. 
Altthal,  Transyl- 
vania. 

A.  Cossa. 
F.  Koch. 
J.  Barber, 
f  A  Schrutter 

Ric.  Chim.  Roc.  Italia, 
1881,  p.  111. 
Min.   Mitth.,   1883  (2), 
v.  243. 
Sitz.  Wien.  Akad.,  1867, 
Ivi.  266-275. 

3.20 

I    3.009  ) 
\    3.677  ] 
2928 

3295 

42.70 
42.74 
42.77 
4280 

2.84 
trace. 

7.48 

7.93 

1.03 
3.34 

7.44 
20.86 
4.79 
9.40 

3.18 
2.78 
0.50 

Dun  Mt.,  near  Nel- 
son, New   Zea- 

1864, xvi.  341-344. 

3295 

4269 

10.09 

Picrite. 

land. 
Siilile,    Neutit- 

V  Slechta. 

1864,  xvi.  341-344. 
Sitz  Wien  Akad    1866 

42.85 

10.42 

6.27 

6.86 

11.84 

scliein,  Mora  via. 

liii.  (1),  270. 
Phil   Mig     1855  (4)   x 

4288 

3.80 

Switzerland. 

254. 
Min  Mng    1879  ii  194 

42.91 

0.05 

0.77 

2.90 

0.02 

Picrite. 

land. 
Ty  Croes,  Angle- 
sey. 

J.  A.  Phillips. 

Quart.  Jour.  Geol.  Soc., 
1883,  xxxix.  256. 

2.88    j 

42.94 
42.79 

10.87 
10.98 

.... 

.'1.47 
3.40 

10.14 
10.13 

9.07 
9.15 

*  The  prefixed  asterisk  indicates  that  the  specimen  is  a  meteorite. 


ANALYSES  OF  METEORIC  AND  TERRESTRIAL  ROCKS. 


XXIX 


Coidiintul. 


Mi;<). 

MnO. 

.Yl.O. 

K.O. 

Cr;10a. 

Ni. 

Co. 

Cu. 

Sn. 

P. 

S. 

U.f>. 

Miscellaneous. 

Total. 

IS  IL' 

0.24 

0.93 

5.00 

10063 

41  TO:! 

0.2:3 

1243 

99478 

NiO 

CO2  —  051   Ignition  —  1  1  88 

10045 

4  '.I  -.'I 

NiO 

0.34 

10060 

•s',  si 

II  -'S 

U) 

050 

1  45 

0.05 

Graphite  —  0.26    S+P+Cr/}. 

10000 

24.il 

0.18 

1.70 

trace. 

0.64 

1.04 

2.27 

=  2.02. 
NiO  —  0  00     Recalculated. 

10085 

M.97 

trace. 

1.20 

902 

COj  —  0  86 

10023 

:;i  r-2 

0.32 

4.95 

101.09 

lo-'t; 

1158 

10087 

4°  1-3 

0.18 

NiO 
025 

655 

10155 

1000 

1.50 

NiO 
1.23 

1.00 

10450 

21.11 

trace. 

1.00 

CrjOrr-FcO 
"  0.5)1 

0.64 

2.17 

Recalculated. 

98.08 

4!>.l:'. 

mo 

0.35 

CrjOs-l-FeO-t-SKJj  —  0  58   Ig- 

100.21 

4'.)  18 

039 

nition  =  0  82. 
CtyOb+FeO-l-8iO<  •  —  1  83  Ig- 

10018 

31.40 

trace. 

7.094 

nition  =  0.70. 

99951 

20.97 

0.36 

0.44 

Cr.,0,+FcO 

"  4.08 

6.64 

100.20 

21.81 

.Mn 

tnusc 

-.    . 

0. 

,  ' 
J3 

1.32 

0.01 

trace. 

trace. 

006 

10101 

11.91 

.Mn 
trace. 

0. 

)86 

1.322 

0.045 

trace. 

0.001 

0.113 

101.264 

8.873 

230 

1  184 

0035 

103.819 

U41 

Mn 

tract-. 

0.235 

NiO  —  0.812. 

99.501 

38.90 

trace. 

trace. 

Ignition  —  9  42 

10000 

40.83 

trace. 

100.13 

28.90 

0.85 

Cr..(),+FeO 
"13.27 

1207 

10026 

uiaa 

Undt. 

Undt. 

2.00 

0.08 

98.08 

42.:M 

1364 

100.78 

4:!  10 

13  69 

1(1084 

42.97 

1348 

100.69 

42..'iii 

13.70 

100.83 

•!".  o 

1300 

10086 

87.50 

0.25 

3.54 

98.54 

16.96 

30.11 

1.12 

1.20 
0.50 

0.21 
0.10 

Cr^Oa+FeO 
1.50 

trace. 

1.38 

trace. 

.... 

.... 

0.41 

2.61 

328 

Mn  =  0.57,  Li2O=  trace,  C?  = 
0.19. 

09.51 
98.87 

47.:J8 

trace. 

NiO 
trare. 

067 

CoO  —  trace. 

100.16 

40.90 

Ni 
trace. 

049 

100.17 

9.01 
40..32 

.... 

1.65 

1.01 



.... 

.... 

.... 

i'A 

trace. 

.... 

2.70 
1204 

Cl  =  trace,  CO.2  =  6.88.  Rock 
altered. 

99.09 
99.84 

40.04 

0.18 

11  89 

99.96 

IMS 

trace. 

0.90 

0.15 

!'.", 

344 

TiO2  —  trace  CO2  —  2  65. 

99.95 

10.22 

(race. 

0.93 

0.10 

3  4.'! 

TiO^  —  trace  COj  —  2.05. 

IMP 

XXX 


A  CLASSIFIED   LIST   OF   COMPLETE   (BAUSCH) 


TABLE  IV. 


Variety. 

Locality. 

Analyst. 

Publication. 

Sp.  Gr. 

Si0.2. 

A1203. 

Fe. 

Fe203. 

FeO. 

CaO. 

Lherzolite. 

Dreiser  Weiher, 

C.  Rammelsberg. 

Ann.   Physik    Chemie, 

4298 

1.74 

859 

•J  .;() 

Meteorite. 
Serpentine. 
Serpentine. 
Serpentine. 

Eifel. 

Lissa,  Bohemia. 

Westfield,  Mass. 

Germagnano, 
Piedmont. 
Gornoschit,    Rus- 

M.  H.  Klaproth. 
E.  Hitchcock. 
A.  Cossa. 
F.  v.  Schaffgotsch. 

1870,  cxli.  Sl'2-519. 
Bei  trage  M  ineralkorper, 
1810,  v.  246-253. 
Geol.  Mass.,  1841,  p.  160. 

Ric.  Chim.  Rnc.  Italia, 
1881,  pp.  121,  122. 
Rose,  Reise  nach  dem 

3.56 
2.615 

43.00 
43.03 
43.44 
43  734 

1.25 

0.42 
0813 

29.00 

8.08 
0.91 

2.84 
6  111 

0.00 

Serpentine. 

ila. 

East  Goshen, 

S.  P.  Sharpies. 

Ural,  1857,  i.  245. 
Am.  Jour.  Sei.,  1806  (2) 

4389 

1  38 

Meteorite. 
Serpentine. 
•Lherzolite. 
Meteorite. 
Meteorite. 

Chester  Co., 
Penn. 
Sienna,  Italy. 

Haaf-Grunay    Is- 
land, Scotland. 
Knyaliinya,  Hun- 
gary. 
Danville,    Alaba- 
ma. 
Uden,  North  Bra- 

M. H.  Klaproth. 
M.  F.  Heddle. 

E.   H.   von    liaiiin- 
hauer. 
J.  L.  Smith. 

Baumhauer   and 

xlii.  272. 

Mem  .  A  cad  .  Berlin,  1803, 
pp.  38-42. 
Min.  Mag.,  1870,  ii.  IOC. 

Archives    Nc'erland., 
1872,  vii.  146-153. 
Am.  Jour.  Sci.,  1870  (2), 
xlix.  !K)-93. 
Ann.    Physik    Chemie, 

3.34-3.40 

3.515 
3.398 
3.4025 

44.00 
44.003 
44.30 
44.47 
44.579 

3.057 
1.68 
4.10 

2.25 
2.58 

0.108 

25.00 
6.286 
16.379 
23.44 
22.409 

•2.727 
0.22 
2276 

Serpentine. 

bant. 
Saxony. 

Seelheim. 
A.  Vogel. 

1862,  cxvi.  184-188. 
Gelehrte  Anzeig.  Mun- 

.J 

44.70 

1.24 

13.20 

Meteorite. 
Meteorite. 

Meteorite. 

Harrison  Co.,  In- 
diana. 

L'  Aigle,  Orne, 
Prance. 

Sauguis-Saint- 

J.  L.  Smith. 

{E.   H.   von    Baum- 
hauer. 
Foucroy   and    Vau- 
quelin. 
S.  Meunier. 

chen,  1844,  xix.  115, 
116. 
Am.  Jour.  Sci.,  1859  (2), 
xxviii.  409-411. 
Archives     Nc'erland., 
1872,  vii.  154-160. 
Ann.   Mus.    Hist.  Nat., 
1804,  iii.  101-108. 
Comptes  Rendus,  1808, 

1 

3.405 
3.607 
3.49-3.626 
3.309 

43.10 
44.80 
44.81 
53.00 
44.879 

1.94 
2.23 
2.34 

4.26 

36.00 

15.60 
24.80 
18.34 

4.022 

0.77 
4.03 
1.00 
050 

Lherzolite. 
Meteorite. 

Etienne,  Mau- 
le'on,  France. 
Vicdessos.France. 

Forsyth  Georgia. 

H.  A.  v.  Vogel. 
C.  U.  Shepard. 

Ixvii.  873-877. 

Jour.  Mines,1813,xxxiv. 
71-74. 
Am.  Jour.  Sci.,  1848  (2), 

3.25-3.333 

45.00 
45.00 

1.00 
1.62 

8.90 

12.00 

29.90 

19.50 
4  77 

Meteorite. 
Lherzolite. 

Bremerviirde, 
Hannover. 
Baldissero,    Pied- 

F. Wohler. 
A.  Cossa. 

vi.  406,  407. 
Ann.    Chemie    Pharm., 
1856,  xcix.  244-248. 
Ric.  Chim.  Roc.  Italia, 

3.64 

2.269 

45.40 

45.68 

2.34 
6.28 

21.61 

.... 

4.36 
9.12 

Undt. 
2.15 

Picrite  (Pa- 
laeopicrite). 
Meteorite. 

mont. 
Ottenschlag,  Aus- 
tria. 
Moresfort,  Tippe- 

A.  Gamroth. 
W.  Higgins. 

1881,  p.  105. 
Min.Mitth.)1877,p.278. 

Phil.Mag.,1811,xxxviii. 

(  3.67 

45.03 
46.00 

15.09 

42.00 

1.87 

11.45 

8.92 

262-268. 

(  3  6478 

48.25 

39.00 

Lherzolite. 

land. 
Corio,  Piedmont. 

A.  Cossa. 

Ric.  Chim.  Roc.  Italia, 

3.225 

46.46 

2.85 

15.22 

3.35 

J.  S.  Brazier, 

1881,  pp.  100,  110. 
Neues  Jahr  Min.  1879, 

47.15 

0.90 

3.40 

9.56 

1.61 

Peridotite. 

St.  Paul's  Rocks, 
Atlantic  Ocean. 

L.  Sipiicz. 
J.  S.  Brazier. 

pp.  390-394. 
Rep.  Challenger  Exp., 
Narrative,    1882,    ii., 
App.  B. 
Rep.  Challenger   Exp., 

3.287 

43.84 
43.50 

1.14 
0.38 

.... 

1.92 

8.76 
8.01 

1.71 

C.  U.  Shepard. 

Narrative,    1882,    ii., 
App.  B. 

300-3.66 

56.168 

1.797 

18.108 

trace. 

North  Carolina. 

Sci.,  1850,  iii.  149-152. 

*  The  prefixed  asterisk  indicates  that  the  specimen  is  a  meteorite. 


ANALYSES  OF  METEORIC  AND  TERKESTRIAL  EOCKS. 


XXXI 


Continued. 


KgO. 

MnO. 

No,O. 

K/>. 

Cr20s- 

Ni. 

Co. 

Cu. 

Sn. 

P. 

S. 

HjO. 

Miscellaneous. 

Total. 

4"  .",'» 

Cr,0,,  +  FeO 
100 

99.19 

2200 

Mb 

0°5 

050 

S+loss  —  3  50. 

10000 

13.93 

Loss  —  0.42. 

100.00 

41  15 

1206 

100.82 

37710 

11.626 

100.00 

4048 

13.45 

99.20 

2200 

025 

000 

Loss  —  5  40. 

10000 

80714 

trace. 

13.20 

100.311 

2°  10 

100 

0658 

O2O,-i-FeO 
080 

FeS  —  2.22      Fe+Ni  —  5  00. 

98.282 

20.09 
20GG7 

trace. 
043 

0.49 
094 

0.62 
0.49 

trace. 
Cr.,O3+FeO 
"0  70 

0.28 
NiO 
029 

0.01 

trace. 

.... 

trace. 

0.98 

.... 

Recalculated. 
Li.jO  =  trace.    Recalculated. 

Ni+Fe+S—  1.707  FeS—  0.718. 

99.84 
99.424 

•'-:  :.n 

0145 

11  20 

C  —  o  192 

99277 

l!ii  "D 

0  17 

1240 

C  —  0  20. 

'J'J  01 

trace. 

0.40 

065 

065 

0.02 

trace. 

trace. 

trace. 

Recalculated. 

104.80 

1993 

123 

085 

OoO.+FeO 
000 

Fe+Ni  —  8.00,      FeS  —  1.80 

101.93 

900 

300 

2.00 

Recalculated. 

104.00 

39409 

trace 

0454 

0012 

Al»0,+FeoO-,  —  0604,  Fe-f-Ni 

100.574 

1600 

050 

=  8.05,  FeS  =  3.044. 
Loss  —  0  00 

10000 

8.37 

096 

Cr.2O,-(-lo8s  —  0.14.      Recalcu- 

99.60 

2240 

Undt 

118 

037 

Cr.,O,+FeO 
"031 

1  89 

Undt 

Undt 

Undt 

lated. 
Graphite  —  0.14. 

10000 

34.76 

0.26 

121 

9946 

1482 

1.93 

022 

058 

lOO'.Sl 

12.25 

1  50 

400 

105.75 

900 

1  70 

400 

10200 

3008 

trace. 

072 

99.28 

36.69 

Loss  —  0.50,  CaS  —  0.29. 

100.00 

41.:;:; 

0.12 

0.42 

NiO 
100  x 

106 

101.89 

KM 

CaSO4  —  0.96,  CasP2O8=  0.28, 

100.00 

10.400 

trace. 

trace. 

OCO.  —  0.47,     Ignition  = 
4.20. 
Fe+Ni  —  6.32,     FeS  =  3.807, 

100.00 

Loss  =  3.394. 

XXX11 


A  CLASSIFIED   LIST  OF   COMPLETE   (BAUSCH) 


TABLE  V.  — Basalt. 


Variety. 

Locality. 

Analyst. 

Publication. 

Sp.  Gr. 

Si0.2. 

AL,08. 

Fe. 

Fe203- 

Basalt. 
Basalt. 

Basalt. 

Basalt. 

Gabbro. 

.,    I'' 

Gabbro. 

onzac,  France. 

Stannern,    Iglau, 
Moravia. 

Constantinople, 
Turkey, 
'etersbnrg,    Lin- 
coln Co.,  Tenn. 

Tuvenas.Ardeclie, 
France. 

Shergotty,  India. 

Charkow,  Russia. 

Frankfort,  Frank- 
lin Co.,  Alabama. 
Kulesi'linwka.Pol- 

A.  Laugier. 
C.  Rammelsberg. 
M.  H.  Klaproth. 
J.  Moser. 
L.  N.  Vauquelin. 
E.  Ludwig. 
J.  L.  Smith. 
{C.  Rammelsberg. 
A.  Laugier. 
L.  N.  Vauquelin. 
f  E.  Lumpe. 
1  F.  Crook, 
f  J.  Scheercr. 

1  Suhnaubert    and 
Giese. 
G.  J.  Brush. 

J.  Scheercr. 
C.  Riimmelsberg. 
-  N.  S.  Maskelyne. 
H.  Fiildington. 
f  N.  S.  Maskelyne. 
[  W.  Dancer. 
f  A.  Sclnvager. 
ilmhof. 
N.  S.  Maskelyne. 
R.  Prendel. 
G.  vom  Rath. 
C  Rammelsberg. 
J.  L.  Smith. 

W.  S.  v.  AValters 
liausen. 
{  C.  V.  Shcpard. 

M<5m.  Mus.  Hist.  Nat.,  1820,  vi.  233-240. 
Ann.  Physik  Chemie,  1851,  Ixxxiii.  591-593. 
Beitrage  Mineralkorper,  1810,  T.  257-263. 
Ann.  Physik,  1808,  xxix.  309-327. 
Ann.  Chimie,  1809,  Ixx.  821-330. 
Min.  Mitth.,  1872,  pp.  85-87. 
Am.  Jour.  Sci.,  1861(2),  xxxi.  264-266. 
Ann.  Physik  Chemie,  1848,  Ixxvii.  585-590.  ' 
Ann.  Chimie  Phyi^WBl,  xix.  26^-273. 
Ann.  Chimie  Phys.,  1821,  xviii.  42H23. 
Min.  Mitth.,  1871,  pp.  55,  50. 
Chem.  Const.  Met.  Stones,  pp.  30-33. 

Me'm.  Acad.   St.  Pe'tersbourg,   1813-14,  vi 
Hist.,  p.  47. 
Ann.  Physik,  1809,  xxxi.  316-322. 

Am.  Jour.  Sci  ,  1869  (2),  xlviii.  240-244. 

Me'm.  Acad.  St.  Pe'tersbourg,  1812,  v.,  Hist, 
pp.  22,  23. 
Mon.  Berlin.  Akad.,  1870,  pp.  316-322. 

Phil.  Trans.,  1871,  clxi.  366,  367. 
Jour.  Asiat.  Soc.  Bengal,  1851,  xx.  209-314. 
Phil.  Trans.,  1870,  cxl.  193-211. 
Phil.  Trans.,  1870,  cxl.  193-211. 
Sitz.  Miinchen  Akad.,  1878,  viii.  32-40. 
Sitz.  Munchcn  Akad.,  1878,  viii.  34. 
Phil.  Trans  ,  1870,  clx.  211-213. 

Me'm.  Sci.  Nat.   Cherbourg,   1877-78,  xxi 
203-207. 
Sitz.  nicder.  Gesell.  Bonn,  1871,  xxviii.  142- 
145. 
Mon.  Berlin.  Akad.,  1861,  pp.  895-900. 

Am.  Jour.  Sci.,  1864  (2),  xxxviii.  225,  220. 
Ann.  Chemie  Pharm.,  1851,lxxix.  369-374. 
Am.  Jour.  Sci.,  1846  (2),  ii.  380,  381. 

3.12,  3.0773, 
3.0897 

2,90-3.20 
2.95-3.16 
3.077-3.1529 
3.19 
3.17 
3.20 

3.099-3.148 

40.00 
48.30 
48.25 
46.25 
50.00 
48.59 
49.21 
49.23 
.  40.00 
40.00 
50.21 
36.211 
51.00 
48.00 
51.33 
52.00 
52.64 
4537 

6.00 
12.65 
14.50 
7.62 
9.00 
12.63 
11.05 
12.55 
10.40 
13.40 
5.90 
1.871 

36.00 

23.00 

27.00 
29.00 

0.50 
0.16 

1.21 

23.50 

8.143 
19.80 

3.00 
3.4902 
3.31 
3.539 
3.412 

21  78 

Basalt. 

8.05 
1.60 

trace. 
10.00 

18.40 

Gabbro. 

Gabbro. 

Gabbro. 
Gabbro. 

tawa,  Russia. 
Shalka,  India. 

Busti,  India. 
Massing,  Bavaria. 

3.66 

C8.60 
52.871 

0.60 

26.80 

5273 

3.3636 
3.365 
3.198 

53.115 
31.00 
53.629 
53.81 
54.49 

57.52 

I  00.12 
)  5'.).83 

07.140 
70.41 

8.204 

0.52! 
1.80 

32.54 

dt'ish,  India. 

8.75 
1.06 

2.72 

9.41 

Gabbro. 
Gabbro. 

son,  Russia. 
IbhenbiireM, 
Westplmlia. 

Bishopville.Soutl 
Carolina. 

3.40-3.43 

O.SO 
0.50 

1.706 

3.039 
3.116 

1.478 



ANALYSES   OF   METEORIC   A^D   TEEEESTEIAL   EOCKS. 


XXXlll 


Part  I.    The  Meteoric  Basalts. 


FeO. 

CaO. 

MgO. 

Mn<>. 

Na,O. 

K,0. 

Cr,03. 

NL 

P,06- 

S. 

H20. 

Miscellaneous. 

Total. 

7.50 

1.00 

2.60 

1.00 

1.60 

10240 

10.83 

11.27 

6.87 

0.81 

O.M 

0.23 

Cr2O3+FeO 
0.64 

FcS  —  trace.  . 

10061 

9.50 

2.00 

Loss  —  2.75  

10000 

!•-'  12 

2.50 

0.75 

Cr,08 
trace. 

Loss  —  3.76. 

10000 

12.00 

1.00 

" 

10100 

2099 

lo:;:i 

6.10 

trace. 

0.46 

0.16 

Cr2O3+FeO 
0.44 

FeS  —  trace 

9982 

20.41 

•'(>:::; 

9.01 
10.2! 

8.13 
0.44 

0.82 
0.63 

0.12 

0.24 

trace. 

P 

trace. 

0.28 

0.06 
0.09 



TiO2  —  0  10. 

99.23 
101  61 

9.20 

0.80 

6.50 

0.20 

1.00 

0.50 

Cu  —  010  ..   . 

9220 

*- 

8 

*  ' 
00 

Na,O+K,O-f-Cu+Cr,03+S  —  11  60 

10000 

21.85 

10.41 

10.00 

1.28 

O.C7 

Fe+Mn  =  27.00. 

10022 

'21  I0"i 

0.4:!o 

24.114 

0223 

0.109 

0.237 

1.30 

P 

trace. 

trace 

99778 

20.50 

1  60 

Mn2O3  —  4  20    Loss  —  3  00 

10000 

22.05 

1.00 

Mn2O,  —  6.00  

9943 

1370 

7.03 

17.59 

0.45 

0.22 

0.42 

023 

9902 

960 

1  20 

425 

CaO  +  Mn  0  -floss  —  2  95 

10000 

18.78 

0.55 

26.38 

0.40 

023 

Mean  analysis  of  the  crust  and  interior. 

9998 

19.06 

2.214 

15.636 

Cr  ,O3+FeO  —  17.717.  .   . 

99997 

2.00 

010 

012 

98  12 

0194 

I"::'.i7 

28.321 

0.573 

0.°39 

Li,O  —  0019    CaS  —  4133    CaS04  — 

100  18 

4.28 

lli  i::s 

1.18 
6.780 

37.22 

8.485 

0.01 

1.928 

trace. 
1.188 

0.979 

XiO 
0.78 

trace. 



0.374 

0.02 

0.442. 
CaCl  =  0.01  ,  Na.2S  =  0.76,  Li/)  =  trace, 
CagPOg  =  trace,  CaS04  =  1.58. 

99.47 
9972 

23.25 

135 

Loss  etc  —  10  06 

10000 

20.476 

1.495 

23.32 

Cr.,03-t-FcO 
"  1.02'J 

00  949 

2.07 

18.54 

trace. 

^7 

V  ' 

14 

trace. 

0.70 

FeS  —  5.26  

99  08 

IT.  'U 

1.22 

20.12 

0.28 

10077 

1.25 

0.66 

34.80 
KM 

0.20 

1.14 
0.74 

0.70 
tnice. 











Ignition  =  0  80  

99.79 
10061 

:v.<  i"J 

074 

trace. 

10029 

1.818 

.'7.115 

trace. 

0671 

99  ys 

28.25 

1  30 

10005 

PLATE  I. 

FIG.  1.     Pallasite.    ATACAMA,  BOLIVIA. 

PACKS 

A  tracing  made  from  the  polished  surface  of  a  specimen.  The  coloring  is  conventional  in  this 
and  in  the  next  three  figures.  The  yellow  portions  are  the  olivine  grains,  while  the  gray 
reticulated  portion  indicates  the  metallic  iron  and  pyrrhotite,  —  since  no  distinction  of  the 
different  constituents  was  possible  in  a  tracing  except  to  divide  them  into  silicates  and 
metallic  portions 70 

FIG.  2.    Pallasite.    KRASNOYARSK,  SIBERIA. 
Tracing,  as  in  Fig.  1 71,  72 

FIGS.  3,  4.    Pallasite.    RITTERSGRUN,  SAXONY. 

Tracings  of  two  opposite  sides  of  the  same  polished  slab.     All  these  tracings  are  of  natural  size 

and  form,  so  far  as  it  was  possible  to  make  them 72,  73 

FIG.  5.    Pallasite,  —  Cumberlandite.    IUON  MINE  HILL,  CUMBERLAND,  RHODE  ISLAND. 

A  slightly  magnified  portion  of  a  section.  The  dark  portions  represent  magnetite,  and  the  light 
parts  the  oliviue  with  a  minute  portion  of  feldspar.  While  in  the  four  preceding  figures  the 
sponge-like  structure  of  the  metallic  parts  with  the  enclosed  silicates  could  alone  be  shown, 
in  this  and  in  the  following  figures  the  minerals  are  in  general  differentiated,  and  the  fidelity 
of  the  lithographer's  work,  in  representing  the  form,  structure,  fissuring,  coloring,  etc.  of  the 
natural  section,  will  be  appreciated  by  all  familiar  with  such  rocks.  This  figure  shows  the 
same  sponge-like  structure  as  the  preceding  figures,  but  with  the  metallic  iron  replaced  by 
its  oxidized  form 75,  76 

FIG.  6.    Pallasite,  —  Cumberlandite.    IRON  MINE  HILL,  CUMBERLAND,  RHODE  ISLAND. 

This  figure  is  from  a  section  of  the  same  rock-mass  as  the  preceding,  and  shows  the  same  general 
structure ;  but  the  olivine  of  Fig.  5  is  here  replaced  by  serpentine,  which  retains  the  outlines 
of  the  former,  and  marks  its  fissures  by  secondary  magnetite  grains 78,  79 


MEM  MUSEUM  COMPZOOL  VOL. XI. 


PLATE 


3. 


fc  TOsytw, 

i  *5gftlw 

*^*^t^\*V  ••«  9 


4. 


(i. 


MEWadiworth.dd 


A-JInnel  hlKBoiun 


PLATE  II. 

Fio.  1.    Pallasite,  —  Cumberlandite.     IRON  MINE  HILL,  CUMBERLAND,  RHODE  ISLAND. 

PAGES 

This  figure  illustrates  a  more  highly  magnified  intermediate  stage  in  the  same  rock-mass,  lying 
between  that  presented  in  Figs.  5  and  6  of  Plate  I.  The  dark  portion  represents  the  mag- 
netite sponge  which  holds  the  lighter  silicates.  The  brownish  portion  represents  the  smoky, 
fissured,  somewhat  altered  olivine,  which  is  surrounded  by  a  grayish  and  white  actinolite, 
produced  by  the  alteration  of  the  olivine  on  its  borders.  The  ragged  character  of  the  mag- 
netite borders,  as  shown  in  the  figure,  also  indicates  that  it  is  associated  in  the  change,  or 
affected  by  the  alteration 77,  78 

FIG.  2.     Pallasite,  —  Cumberlandite.     TABERG,  SWEDEN. 

This  shows  the  same  general  structure  of  magnetite  enclosing  silicates,  principally  olivine,  as 
the  three  preceding  figures.  The  reddish-brown  spots  at  the  bottom  of  the  figure  represent  a 
secondary  mica  (biotite)  produced  in  connection  with  the  magnetite 81 

FIG.  3.    Pallasite,  —  Cumberlandite.    TABERG,  SWEDEN. 

This  figure  represents  a  more  highly  altered  portion  of  the  same  section  as  that  shown  in  Fig.  3. 
The  magnetite  is  less  in  amount,  having  been  partially  removed,  and  the  reddish-brown 
biotite  more  abundant,  while  the  silicate  portions  are  more  altered.  81 

FIQ.  4.    Peridotite,  —  Saxonite.    IOWA  COUNTY,  IOWA. 

The  grayish  and  brownish  parts  represent  the  granular  groundmass  of  olivine  and  enstatite 
sprinkled  with  ferruginous  particles  and  enclosing  the  steel-gray  masses  of  metallic  iron. 
The  orange-brown  represents  the  ferruginous  staining.  A  little  to  the  right  of  the  centre 
of  the  figure  is  represented  an  olivine  cliondrus  composed  of  the  colorless  olivine  grains  held 
in  a  grayish  base 86-88 

FIG.  5.     Peridotite,  —  Saxonite.     IOWA  COUNTY,  IOWA. 

This  represents  one  of  the  larger  chondri,  composed  of  olivine  and  enstatite,  which  blends  at  the 
lower  portion  of  the  figure  with  the  general  groundmass.  The  enstatite  and  olivine  grains 
are  held  in  a  gray  base,  which  is  here  given  too  dark  a  shade.  The  metallic  iron  and  the 
ferruginous  staining  are  represented  by  the  steel-gray  and  orange-brown  colors 86-88 

FIG.  6.    Peridotite,  —  Saxonite.    KNYAHINYA,  HUNGARY. 

This  shows  a  granular  groundmass  of  chondri  and  olivine  and  enstatite  grains,  partially  stained 
by  ferruginous  material  to  an  orange-  and  yellowish-brown.  One  chondrus  is  shown  extend- 
ing from  the  centre  towards  the  right  of  the  figure,  which  consists  of  a  fan-shaped  mass  of 
grayish  fibrous  base,  held  in  and  cut  by  enstatite  bars.  At  the  base  is  shown  a  portion 
of  another  chondrus  composed  of  radiating  bands  of  enstatite  and  base.  Towards  the  bottom 
of  the  figure,  and  at  the  left  of  the  centre,  is  shown  an  elongated  fissured  enstatite  crystal.  The 
metallic  iron  grains  are  indicated  as  before.  .  ...  ...  88-91 


MEM  MUSEUM  COMP  ZOOL.VOL.XI. 


PLATE 


il  t  Wldiworth  d«l 


PLATE  III. 

FIG.  1.    Peridotite,  —  Lherzolite.     PULTUSK,  POLAND. 

PAGES 

This  shows  a  portion  of  a  section  with  two  chondii  at  tlie  base  of  the  figure,  while  the  remaining 
upper  portion  is  made  up  of  an  aggregate  of  cliondri,  olivine,  enstatitc,  dial  luge,  pyrrhotite, 
and  iron  grains.  The  larger  and  darker  chondrus  is  composed  of  aggregately  polarizing 
fibrous  enstatitic  material.  This  chondrus  shows  rounded  indentations,  and  on  its  left  is 
another  form,  composed  of  alternating  colorless  enstatite  ribs  and  bands  of  gray  base  with 
minute  iron  granules.  The  dark  portions  of  the  figure  represent  the  iron  and  pyrrhotite,  and 
the  yellowish-brown  the  ferruginous  staining 94,  95 

FIG.  2.     Peridotite,  —  Lherzolite.     PULTUSK,  POLAND. 

This  displays  the  structure  of  a  chondrus  composed  of  olivine,  enstatite,  iron,  etc.,  cemented  by  a 
gray  base.  This  chondrus  occupies  the  chief  portion  of  the  figure,  but  towards  the  bottom  its 
gradual  passage  into  the  groundmass  is  shown.  The  ferruginous  materials  are  colored  as 
in  Fig.  1 94,  95 

FIG.  3.    Peridotite,  —  Lherzolite.    PULTUSK,  POLAND 

The  brownish-black  central  portion  is  pyrrhotite  surrounding  a  steel-gray  pear-shaped  mass  of 
metallic  iron.  Surrounding  the  pyrrhotite  is  the  chondritic  groundmass  of  the  meteorite, 
partially  stained  yellowish-brown 94,  95 

. 

FIG.  4.    Peridotite,  —  Saxonite.    WACONDA,  KANSAS. 

This  shows  a  mixed  granular  groundmass  of  olivine,  enstatite,  iron,  and  pyrrhotite,  which  is 

more  or  less  stained  a  yellowish-  and  reddish-brown  from  the  oxidation  of  the  iron 93,  94 

FIG.  5.    Peridotite,  —  Lherzolite.     ESTHERVILLE,  EMMET  Co.,  IOWA. 

This  shows  a  grayish  and  a  greenish-yellow  groundmass  of  olivine,  enstatite,  and  diallage,  with 

dark-colored  iron  and  pyrrhotite,  surrounding  a  larger  crystal  of  diallage 97—101 

FIG.  6.    Peridotite,  —  Lherzolite.    ESTHERVILLE,  EMMET  Co.,  IOWA. 

This  represents  a  semi-sponge-like  mass  of  iron  and  pyrrhotite  with  enclosed  grains  of  olivine, 
diallage,  and  enstatite.  On  the  left  is  figured  a  crystal  of  enstatite  with  its  inclusions  and 
characteristic  cleavage  ;  while  on  the  right  is  a  crystal  of  diallage  showing  its  cleavages. 
The  yellowish-brown  ferruginous  staining  is  to  be  seen  in  some  portions  of  the  figure.  .  .  .  97-101 


MEM  MUSEUM  COMPZOOL  VOL. XI. 


PLATE 


. 


a  E  Widiworth  it. 


PLATE   IV. 

FIG.  1.    Peridotite,  — Lherzolite.    NEW  CONCORD,  GUERNSEY  Co.,  OHIO. 

PAGES 

This  shows  a  grayish,  crystalline,  granular  mass  of  olivinc,  enstatite,  and  diallage,  containing 
dark  grains  of  iron  and  pyrrhotite.  The  grouudmass  is  stained  by  the  oxidation  of  the 
iron  to  a  reddish-  and  yellowish-brown 95,  96 

FIG.  2.     Peridotite, — Dunite.     FRANKLIN,  NORTH  CAROLINA. 

This  figure  represents  a  granular  mass  of  olivine  traversed  by  fissures,  giving  it  a  grayish  appear- 
ance. A  little  below  the  centre,  and  also  on  the  left  of  the  figure,  are  two  dark  chromite 
grains.  This,  with  the  ten  preceding  figures,  presents  the  structure  of  the  unaltered  peridotites.  118 

FIG.  3.     Peridotite,  —  Duiiite.    WEBSTER,  NORTH  CAROLINA. 

This  represents  ar.  early  stage  in  the  alteration  of  the  peridotites,  in  which  a  greenish  and 
yellowish  fibrous  serpentine  has  been  formed  along  the  fissures  of  the  olivine,  leaving  color- 
less grains  in  the  interstices  of  the  serpentine  network.  A  further  stage  in  the  alteration  is 
the  change  of  some  of  the  interstitial  grains  to  a  pale  yellow  serpentine.  The  reddish-brown 
grains  sprinkled  with  black  granules  show  the  picotite,  while  the  minute  Ijlack  grains  in  and 
about  the  serpentine  indicate  the  magnetite  produced  during  the  process  of  the  conversion  of 
the  olivine  into  serpentine 119,120 

FIG.  4.    Peridotite,  —  Saxonite.     ANDESTAD  SEE,  AURE,  NORWAY. 

This  figures  a  further  change  in  a  peridotite,  in  which  the  chief  portion  is  altered  to  a  greenish 
serpentine  containing  clear  grains  of  unaltered  olivine.  In  the  upper  portion  of  the  figure 
is  a  partially  altered  enstatite  traversed  by  fissures  and  containing  much  secondary  magnetite 
dust.  This  enstatite  is  also  partially  altered  to  serpentine.  Dark  magnetite  dust  is  shown 
in  connection  with,  the  olivine  grains,  while  dark  grains  of  chromite  are  figured  in  the 
serpentine 126, 127 

FIG.  5.    Peridotite,  —  Serpentine.    HIGH  BRIDGE,  NEW  JERSEY. 

This  represents  an  extreme  stage/in  the  process  of  the  alteration  of  a  peridotite,  in  which  is 
shown  a  yellowish  and  grayish  serpentine  mass  blotched  with  aggregations  of  dark  iron-ore 
grains.  Extending  across  the  figure  is  an  irregular  pronged  grayish  band,  formed  by  serpen- 
tinized  olivine  traversed  by  numerous  fissures  filled  with  dust-like  granules  of  iron  ore. 
Enclosed  in  this  gray  band  are  greenish  spots  of  partially  altered  olivine  grains 157 

FIG.  6.    Peridotite,  —  Lherzolite.    JAINA  RIVER,  SAN  DOMINGO. 

This  shows  a  grayish-white  serpentine  mass  holding  dark  patches  of  iron  ore  The  yellowish- 
brown  mass  to  the  right  of  the  centre  is  a  diallage  crystal  altered  to  serpentine,  the  four  white 
spots  indicating  the  unchanged  portions.  The  other  yellowish-brown  and  greenish  spots  are 
serpentinized  pyroxenes  and  olivines,  while  the  gray  irregular  band  on  the  left  is  a  partially 
allured  mass  of  diallage  and  feldspar 140 


MEM  MUSEUM  COMPZOOL  VOL. XI. 


PLATE    IV 


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Fia.  1.    Peridotite,  —  Lherzolite.    COLUSA  Co.,  CALIFORNIA. 

PAGES 

This  represents  one  of  the  earlier  stages  in  the  alteration  of  a  periclotite,  showing  a  fissured  granular 
mass  of  olivine,  enstatite,  and  diallage  traversed  by  a  network  of  pale  grayish  serpentine, 
which  borders  the  fissures.  The  mass  is  traversed  by  brown  bands  of  serpentine,  containing 
iron-ore  dust  along  the  medial  lines.  Dark  grains  of  picotite  or  chromite  lie  in  the  upper 
part  of  the  figure 129-131 

FIG.  2.    Peridotite, — Lherzolite.    COLUSA  Co.,  CALIFORNIA. 

This  shows  a  further  alteration  in  the  same  type  of  rock  as  Fig.  1.  In  this  the  outline  of  the 
olivine  can  be  distinguished  by  the  yellow  serpentine  bands,  while  a  later  formation  of  ser- 
pentine shows  in  the  orange-brown  interior  portions  which  retain  in  part  grains  of  colorless 
unaltered  olivine.  The  brown  serpentine  bands  with  their  medial  line  of  iron-ore  dust  are 
more  abundant  and  better  marked  than  in  Fig.  1  ;  while  much  of  this  secondary  black  dust 
is  disseminated  through  the  section 131,  132 

FIG.  3.     Peridotite,—  Lherzolite.    COLCSA  Co.,  CALIFORNIA. 

The  principal  portion  of  the  figure  represents  a  crystal  of  enstatite  from  the  same  section  as  that 
given  in  Fig.  2.  The  cleavage  lines  with  their  bordering  gray  and  brown  alteration  products 
run  more  or  less  vertically,  —  the  latter  containing  considerable  fine  black  ore-dust.  On  the 
right  and  left  of  the  upper  portion  of  the  figure  are  shown  portions  of  serpentinized  olivine, 
like  that  given  in  Fig.  2.  The  two  portions  are  connected  by  a  yellowish  branching  vein 
of  serpentine.  The  dark  brown  and  black  grains  are  picotite  or  iron  ores 131,  132 

FIG.  4.    Peridotite,  —  Serpentine.    LA  VEGA,  SAN  DOMINGO. 

This  indicates  a  further  stage  of  alteration  than  that  shown  in  Fig.  2.  The  brown  bands  with 
their  medial  ore-dust  remain,  and  are  connected  by  finer  brown  bands  marking  the  fissures 
in  the  original  olivine  ;  while  the  interstitial  olivine  has  been  replaced  by  yellow  serpentine. 
Towards  the  bottom  of  the  figure,  on  the  right  and  left,  are  represented  two  grayish-white 
altered  enstatites.  The  series  is  continued  in  Figs.  2,  4,  and  5  of  Plate  VI.,  and  in  Fig.  2 
of  Plate  VII 154 

FIG.  5.     Peridotite,  —  Serpentine.     HIGH  BRIDGE,  NEW  JERSEY. 

A  grayish-white  mass  of  serpentine  containing  disseminated  dark  iron-ore  grains  and  dust  ;  and 
traversed  by  a  band  of  serpentinized  enstatite  or  diallage  crystals,  which  are  surrounded  and 
cut  by  a  brown  serpentine  holding  black  ore-dust 156,  157 

FIG.  6.     Peridotite,  —  Serpentine.     HIGH  BRIDGE,  NEW  JERSEY. 

This  is  from  the  same  section  as  Fig.  6,  and  contains  the  same  serpentine  groundmass  which,  in 
places,  is  stained  yellow.  Scattered  through  the  groundniass  are  iron  ores  and  brown  ser- 
pentine pseudomorphs  after  olivine  containing  ore-dust,  and  showing  part  of  the  original 
olivine  fissures  by  the  traversing  bands  of  grayish-white  serpentine 156,157 


MEM  MUSEUMCOMPZOOL  VOL. XI. 


PLATE    V 


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A  %1'sel.Ulh.KoMon 


PLATE  VI. 

FIG.  1.    Peridotite,  —  Serpentine.    SANTIAGO,  SAN  DOMINGO. 

PAGES 

This  shows  at  the  base  a  brownish  and  yellowish  reticulated  serpentine  mass,  while  above  lie 
yellowish  and  brown  pseudomorphs  of  serpentine  after  olivine  grains  which  are  surrounded 
and  cut  by  colorless  serpentine.  In  all  the  serpentine  masses,  particularly  the  upper  por- 
tion, are  disseminated  black  grains  and  dust  of  iron  ore 153,  154 

FIG.  2.    Peridotite,  —  Serpentine.    LYNNFIELD,  MASSACHUSETTS. 

This  forms  one  of  a  series  with  Figs.  1,  2,  and  4  of  Plate  V.  In  this  the  brown  serpentine  bands 
no  longer  appear,  but  their  former  position  is  marked  by  the  lines  of  black  iron  ore.  The 
pale  flesh-tint  indicates  serpentine  which  encloses  the  yellowish  central  rounded  spots  of 
serpentine  which  has  replaced  the  last  altered  olivine  grains.  At  the  top  and  bottom  of  the 
figure  are  to  be  seen  patches  of  pale  serpentine  in  which  the  alteration  has  been  carried  so  far 
that  the  yellowish  portions  have  disappeared  and  the  color  been  rendered  uniform,  —  the  con- 
stant tendency  in  the  serpentinization  of  peridotites.  The  black  grains  are  the  iron  ores.  .  .  160 

FIG.  3.     Peridotite,  —  Lherzolite,  —  Serpentine.     PLUMAS  Co.,  CALIFORNIA. 

This  shows  a  yellowish  and  grayish  serpentine  in  which  are  lying  black  iron  ore  and  the  fibrous 

remains  of  enstatite  crystals,  which  are  best  seen  in  the  centre  of  the  figure.1 142 

FIG.  4.     Peridotite,  —  Lherzolite,  —  Serpentine.     INTO  Co.,  CALIFORNIA. 

This  exhibits  a  brownish  reticulated  serpentine,  holding  in  its  interstices  serpentine  of  a  lighter 
color.  This  belongs  to  the  same  series  as  Fig.  2.  In  the  serpentine  lies  a  large  fibrous 
crystal  of  altered  enstatite,  filled  with  black  granules  of  iron  ore  precipitated  during  the  pro- 
cess of  alteration.  The  same  ore  is  also  to  be  seen  in  the  serpentine 132 

FIG.  5.    Peridotite,  —  Serpentine.    PLUMAS  Co.,  CALIFORNIA. 

This  shows  a  grayish-white  reticulated  mass  of  serpentine  containing  disseminated  black  iron-ore 
dust  of  a  secondary  nature  ;  also  some  larger  black  primary  grains  of  iron  ore.  The  upper  half 
of  the  figure  is  traversed  by  veins  of  yellow  serpentine,  one  of  which  cuts  an  iron-ore  grain.  158 

FIG.  6.     Peridotite,  —  Lherzolite,  —  Serpentine.     PLUMAS  Co.,  CALIFORNIA. 

This  figure  is  from  the  same  section  as  Fig.  3,  and  illustrates  the  formation  of  a  serpentine  vein. 
This,  in  the  form  of  a  brownish-yellow  obliquely  banded  serpentine,  crosses  the  central  por- 
tion of  the  figure,  while  heaped  up  on  both  sides  are  to  be  seen  the  aggregations  of  expelled 
iron  ores  mixed  with  yellow  and  colorless  serpentine.1 142 

1  Whitney's  Auriferous  Gravels,  1880,  p.  459. 


MEM  MUSEUM  COMP  ZOOLVOL.XI. 


PLATE   VI 


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PLATE  VII. 

FlG.  1.      Enstatite.     CoLDSA  Co.,  CALIFORNIA. 

PACKS 

This  is  figured  from  the  same  rock  as  Figs.  2  and  3,  Plate  V.  It  indicates  the  manner  in  which 
enstatite  is  altered  to  serpentine.  The  longitudinal  cleavage  runs  from  side  to  side,  and  is 
crossed  hy  the  vertical  fractures.  The  unchanged  enstatite  is  colorless,  but  upon  the  borders 
of  the  cleavage  planes  and  cross  fractures  the  mineral  has  been  altered  to  a  greenish  and 
yellowish  serpentine.  A  yellowish  serpentine  vein  runs  from  the  upper  left-hand  portion  of 
the  figure  to  the  centre  of  the  base 131,132 

FIG.  2.    Peridotite,  —  Serpentine.    WESTFIELD,  MASSCHUSETTS. 

This  continues  the  series  formed  by  Figs.  1,  2,  and  4  of  Plate  V.,  and  Figs  2,  4,  and  5  of  Plate  VI. 
Here  the  serpentine  is  of  a  pale  yellow  without  trace  of  the  usual  network,  and  much  of  the 
black  iron  ore  has  been  arranged  in  the  form  of  a  rectangular  grating 159,160 

FIG.  3.     Peridotite,  —  Lherzolite.     PBESQUB  ISLE,  MICHIGAN. 

This  shows  a  grayish  and  greenish  partially  serpentinized  enstatite  containing  black  iron  ore  and 
holding  rounded  olivines.  These  are  fissured  and  rendered  opaque  in  portions  owing  to  the 
precipitations  of  magnetite  dust  along  the  borders  of  the  fissures.  Greenish  and  yellowish 
serpentine  is  also  to  be  observed  in  connection  with  both  the  enstatite  and  olivine 130 

FIG.  4.     Peridotite,  —  Lherzolite,  —  Serpentine.     PRESQUE  ISLE,  MICHIGAN. 

This  is  drawn  from  a  portion  of  the  same  continuous  rock-mass  as  Fig.  3,  and  represents  a  more 
highly  altered  state  of  the  rock.  The  enstatite  and  diallage  are  largely  replaced  by  greenish 
serpentine,  bluish-green  and  yellowish  biotite  (?),  gray  dolomite,  and  black  iron  ores.  The 
olivines  are  in  part  still  more  opaque  from  the  rejected  iron  ore,  and  they  have  so  far  been 
changed  to  serpentine  that  comparatively  few  clear,  unaltered,  interstitial  fragments  remain. 
The  structure  is  confused,  and  the  distinctness  of  the  minerals  confused  by  the  alteration.  .  136, 137 

FIG.  5.    Feridotite, — Lherzolite,  —  Dolomite.    PRESQDE  ISLE,  MICHIGAN. 

This  is  from  the  same  continuous  mass  of  rock  as  Figs.  3  and  4,  and  displays  a  further  stage  in 
the  alteration.  The  groundmass  is  formed  by  a  grayish  mass  of  secondary  granular  dolomite, 
•which  holds  yellowish,  bluish-green,  and  brown  pseudomorphs  of  serpentine  and  ferruginous 
material  after  olivine 137 

FIG.  6.     Peridotite,  —  Serpentine.    FITZTOWN,  BERKS  Co.,  PENNSYLVANIA. 

This  shows  a  yellow  serpentine  mass  containing  grayish  and  colorless  grains  of  olivine.  The 
brown  masses  represent  secondary  dolomite  grains  formed  in  the  serpentine,  but  the  lithog- 
rapher has  given  them  much  too  dark  a  color,  since  the  grains  figured  are  of  a  cloudy-gray 
to  brownish-gray  color. 152 


MEM  MUSEUM  COMPZOOL VOL. XI. 


PLATE  VII 


2. 


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FIG.  1.     Peridotite,  —  Lherzolite.     BASTE,  HARZ. 

PAGES 

The  first  five  figures  of  this  plate  form  a  series  in  the  order  of  their  numbers,  showing  progressive 
alteration  in  the  same  type  of  rock.  Fig.  1  shows  a  yellowish  enstatite  mass  holding  colorless 
fissured  grains  of  olivine,  some  of  which  contain  brown  picotite  grains.  The.  olivine  cracks 
sometimes  extend  into  the  adjacent  enstatite,  and  even  across  this  into  the  contiguous  olivine. 
The  greenish  color  of  the  enstatite  near  the  upper  right-hand  olivine  grain  marks  an  altera- 
tion state.  The  color  of  the  enstatite  probably  marks  the  beginning  of  a  change 133,134 

FIG.  2.     Peridotite,  —  Lherzolite.     BASTE,  HARZ. 

This  shows  a  further  change  in  the  same  rock  as  Fig.  1.  The  color  of  the  pyroxene  minerals  is 
deeper  and  much  iron-ore  dust  has  appeared,  as  one  of  the  first  products  of  alteration,  along 
the  fissures  of  the  oliviue.  Bands  of  black  ore-dust  and  yellowish  serpentine  cross  the  lower 
portion  of  the  figure.  Yellowish  and  greenish  serpentine  replaces  portions  of  the  silicates.  .  133,  134 

FIG.  3.    Peridotite,  —  Lherzolite.     CHRISTIANIA,  NORWAY. 

A  brownish  altered  enstatite  and  diallage  mass,  holding  greenish  serpentine  pseudomorphs  after 
olivine.  The  structure  produced  by  the  formation  of  the  serpentine  along  the  olivine  fissures 
is  distinctly  shown,  while  colorless  interstitial  fragments  of  olivine  remain  in  portions  of  the 
pseudomorphs.  The  bluish  band  on  the  right  of  the  figure  marks  a  border  of  alteration 
between  the  original  olivine  and  enstatite.  Much  black  iron-ore  dust  is  to  be  seen,  par- 
ticularly in  the  altered  olivine,  but  it  is  not  so  abundant  as  it  is  in  Fig.  2 134,  135 

FIG.  4.    Peridotite,  —  Lherzolite,  —  Serpentine.     GJ^RUD,  NORWAY. 

The  pyroxene  minerals  are  changed,  having  a  brownish  color,  while  in  part  they  are  replaced  by 
a  grayish-white  to  colorless  magnesium-carbonate,  as  shown  on  the  left  of  the  figure.  The 
olivine  is  altered  more  than  it  was  in  the  preceding  figure,  only  a  very  few  granules  remaining 
unchanged  in  the  yellow  serpentine.  The  iron-ore  dust  has  diminished  in  amount,  but 
sufficient  remains  to  mark  the  original  fissures  in  the  olivine.  The  lithographer  in  his  en- 
deavor to  be  exact,  has  reproduced  on  the  left  and  towards  the  bottom  of  the  figure  three 
bubbles  which  were  in  the  balsam,  but  which,  it  is  needless  to  say,  were  not  in  the  original 
drawing 135 

FIG.  5.    Peridotite,  —  Lherzolite,  —  Serpentine.     BASTE,  HARZ. 

This  shows  a  brownish  altered  pyroxene  mass  containing  yellow  serpentine  pseudomorphs  after 
olivine.  The  change  has  progressed  further  here  than  in  the  preceding.  The  serpentine 
has  a  more  uniform  and  paler  color,  the  iron  ore  diminishes  in  amount,  and  the  olivine  is 
entirely  changed 133, 134 

FIG.  6.    Peridotite,  —  Picrite.     HERBORX,  NASSAU. 

On  the  right  of  the  figure  is  a  brownish  augite  crystal  containing  olivine  grains,  some  of  which 
is  altered  to  greenish,  bluish,  and  brownish  serpentine  and  biotite.  Part  of  the  olivines  show 
the  commencement  of  alteration  only  by  the  production  of  iron-ore  dust  and  colorless  serpen- 
tine along  the  fissures.  At  the  base  of  the  augite  is  shown  a  greenish  alteration  product, 
while  a  large  olivine  is  attached  to  the  upper  portion.  The  groundmass  is  a  yellowish,  gray- 
ish, bluish,  and  greenish  serpentine,  holding  partially  altered  olivines,  brown  biotite  scales, 
and  black  iron  ores .  .  150 


MEM  MUStUMCOMPZOOL.VOL.XI. 


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